The classy playmaker played a big part in his side's opener, when his incisive through-pass found captain Shahril Ishak, who slid a shot past Mohd Iqbal Suhaimi to give the hosts the lead.
However, T-Team immediately hit back through skipper Zairo Anuar, who clinically fired into the bottom corner after Badrul Hisani had laid the ball into his path.
Shahril then missed a penalty in the 58th minute, before the LIONSXII were awarded another four minutes from time.
This time around, Shahdan stepped up and made no mistake, handing the Singapore outfit a valuable three points that sees them keep up their chase of Malaysia Super League leaders Kelantan.
Here, ESPNSTAR.com takes a look at the movers and shakers from Saturday's match.
Hyrulnizam Juma'at - 7
Hyrulnizam has deputised capably in the absence of the injured Izwan Mahbud, so much so that it's not certain if the regular first-choice keeper will automatically get his place back once he returns.
The LIONSXII custodian claimed high balls with authority all night long, and produced a good save in the 15th minute to deny Mohd Dzaiddin from distance.
Madhu Mohana - 7
Another decent performance from the right-back who provided his side with plenty of drive down the right.
Was troubled all night long by Dzaiddin but stuck to his task manfully, and even went up the other end to win the LIONSXII's their first penalty, which Shahril couldn't convert unfortunately.
Safuwan Baharudin - 8.5
The young stopper was close to being the best player on the field after a commanding display in the heart of the LIONSXII defence.
Safuwan was unbeatable in the air on the night and as the game wore on, he even took it upon himself to get his side on the front foot, regularly striking long balls straight at the heart of the opposition defence.
Sevki Sha'ban - 6.5
Sevki has looked shaky at the back in recent weeks, most notably in both legs of the FA Cup quarter-final tie against Terengganu.
However, he was steady if unspectacular against T-Team, and his confidence will be boosted by a faultless display.
Shakir Hamzah - 7
The energetic full-back failed to provide his usual drive down the left flank, but what he did offer the LIONSXII was a real target from set-pieces, which was quite surprising considering he isn't exactly the tallest player in the team.
Shakir had three excellent chances from corners in the latter stages of the first half. He wasted the first two when he found himself unmarked in the box and really should have at least hit the target, before forcing a brilliant save from Iqbal with his third effort.
Irwan Shah - 8
Excellent display from the pacy wideman. Despite having been asked to play out of position on the right in recent weeks, Irwan has continued to offer his side the same penetration he usually does on the other flank.
Was a willing runner all night long and when he did get the ball, the 23-year-old put his head down and headed straight for the byline, stretching the T-Team defence in the process.
Isa Halim - 7
Played his role of anchorman to perfection. Hurried the T-Team midfielders into giving away the ball, and retained possession well on a number of occasions by putting his stocky frame to good use.
Shahdan Sulaiman - 9
Statistics can sometimes be deceiving but even if you take away Shahdan's goal and assist, there's no denying the smooth mover was the best player on the field.
Arguably the best passer in the LIONSXII squad, Shahdan showed he was capable of both the simple and the spectacular. And it was the latter which sent Shahril racing clean through in the 51st minute to open the scoring for the hosts.
Known for his cool head despite opponents snapping at his feet, the 23-year-old had to draw on all his composure when he stepped up in the 86th minute and fired his side's winner from the spot.
Safirul Sulaiman (off 67') - 6.5
Not his best performance in a LIONSXII jersey, but Safirul has definitely proven he has what it takes to do a job whenever coach V. Sundramoorthy calls on him.
Showed a couple of nice touches when he was deployed on the left, but his influence waned once he was shifted into the middle.
Sufian Anuar (off 17') - N/A
It was a night to forget for the energetic striker as he seemed to pull a hamstring while attempting to reach a pas and had to be taken off early on.
Shahril Ishak (off 71') - 6
The LIONSXII captain may have continued his good scoring form against T-Team, but it is clear he is not currently at his best.
In his defence, he is still recovering full match fitness after an injury layoff, but he wasted a couple of excellent chances in the first half, when it appeared he didn't have to pace to race towards goal after being played clean through.
Didn't look particularly keen on helping out whenever his side weren't in possession either.
Agu Casmir (on 17') - 3
One does wonder how Casmir continues to be involved in the LIONSXII first-team setup after another awful performance.
Considering his strength and pace, the former Singapore international should have posed a far greater threat to the T-Team backline.
Instead, all he could muster were half-hearted attempts at winning high balls, and on numerous occasions, he dallied too long on the ball and gave away possession when his side were in good positions.
Sundramoorthy was quick to defend his man however, and described Casmir's performance against T-Team as "one of his best". The majority of the 6,871 fans at the Jalan Besar Stadium who jeered and heckled him would beg to differ.
Firdaus Kasman (on 67') - 6.5
Decent display from the central midfielder, who has done well to forget his off-field troubles early on in the season.
Looks very much a capable player, although Firdaus should now be focusing on establishing himself as a regular starter, which is by no means an easy task.
Yasir Hanapi (on 71') - 6
Good to see Yasir back after a lengthy spell on the sidelines, although it will be a while before he offers the LIONSXII the same penetration he did early on in the year.
Mohd Iqbal Suhaimi - 7.5
The T-Team keeper was unlucky to be on the losing side after keeping his side in the game with a couple of excellent stops, including the penalty save from Shahril.
Did well to deny the LIONSXII captain in the 31st minute after he got done quickly at his near post, before pulling off the save of the game five minutes later to keep out Shakir's bullet header.
Shahril Faizal Sharifuddin - 6
T-Team's worst defender on the night. He gave his direct opponent far too much space all evening long, and was at fault for the LIONSXII's opening goal.
Was even more exposed midway through the second half after Irwan was shifted to the left flank.
Bojan Petric - 7
A decent display from the Bosnian defender, who was strong in the air but slightly suspect on the ground.
Norfazly Alias - 8
A brilliant game from Norfazly, who at times seemed on a one-man mission to keep up the opposition attack.
Looks a real natural at defending, something he exhibited in the 43rd minute when he forced Shahril wide after the LIONSXII forward was played through on goal, before blocking the shot with a sliding challenge.
Norfazly also put his body on the line to block a goalbound effort from Safuwan in the second half, before bailing Petric out after the Bosnian had led a long ball bounce, nearly allowing Casmir to sneak through on goal.
Shahrul Ezrain Samsudin - 6.5
Shahrul was solid in defence but when he went forward to support the T-Team attack, his touches let him down.
Badrul Hisani (off 85') - 7
The T-Team right winger was extremely lively in the first half, and was engaged in an intriguing duel with Shakir.
Showed excellent initiative in the 54th minute to retrieve Dzaiddin's over-hit cross, playing it back into the path of his captain who netted the equaliser for the visitors.
Wan Khairul Faiz (off 79') - 7
Steady performance from the Young Turtles anchorman, who had to cover heaps of ground to keep track of Shahdan.
Zairo Anuar Zalani - 8.5
The fact that the 29-year-old only has a handful of caps to his name is a testament to the wealth of creative playmakers Malaysia currently have.
After a quiet opening half-hour, Zairo started to dictate proceedings in the middle of the park, and was always ready to play an incisive ball to the flanks when T-Team were looking to hit on the counter.
Displayed excellent technique to equalise for the visitors when he met Badrul's cut-back with a first-time shot that found its way into the bottom corner.
Mohd Dzaiddin - 8
Dzaiddin may have incurred the wrath of the home fans after going to ground perhaps too easily and a number of late tackles himself.
But there's no denying the Jalan Besar crowd were more annoyed at the threat the speedy left-winger was posing.
Ran at Madhu with intent at every available opportunity and whipped in several dangerous crosses too.
Mohd Fadzly Saari (off 75') - 6.5
Fadzly failed to offer T-Team much of a presence up front, and was unsurprisingly hauled off with 15 minutes to go.
He wasted a golden opportunity to find the back of the net in first-half injury-time when he nodded over after Dzaiddin had played a ball straight onto his head.
Faiz Subri - 7.5
Full credit to Faiz, who never stopped trying despite a lack of supply from his midfielders.
Kept the LIONSXII centre-backs on their toes all night long, although they eventually prevailed.
Wan Mohd Aliff (on 75') - 6.5
Brought on for the ineffective Fadzly but was also unable to pose much of a threat.
Hasbullah Awang (on 79') - 7
Showed a couple of neat touches despite only being on the field for ten minutes. Undoubtedly a class player.
Tengku Hasbullah (on 85') - N/A
Brought on with five minutes remaining but had minimal time to make an impact.