Dawson has found first-team opportunities hard to come by under new manager Andre Villas-Boas, but the defender made the most of his recall in the first half by glancing home a Tom Huddlestone cross to put Spurs ahead.
The England centre-half was then at fault for the Panathinaikos equaliser in the second half, though, as he was outpaced by striker Toche, who beat Hugo Lloris after a brilliant through-ball from Giourkas Seitaridis.
Villas-Boas had made the shock decision to allow Dawson, Spurs' club captain, to leave the club during the transfer window - but the England man turned down the chance to leave in a £9million move to QPR.
It was easy to see why Villas-Boas was keen to get rid of the 28-year-old at times as his shortage of pace, a likely result of his sparse game-time, left him exposed on at least three occasions.
To lay the blame for picking up just a point entirely at Dawson's feet would be wrong, however. Spurs should have had this tie sewn up well before the Toche was allowed to score.
The Londoners, buoyed by last weekend's historic win over Manchester United, dominated for large parts against a poor Panathinaikos team ravaged by injury and well short of confidence after winning just one game this term.
Jermain Defoe, Clint Dempsey and Huddlestone all went close to scoring, but Tottenham took their foot off the accelerator in the second half and ended up hanging on for a draw that leaves them with just two points from their opening two Group J games.
A Spurs victory seemed certain from the off. Cheered on by the 550 fans who had made the four-hour flight from London, the away side started strongly and should have had a penalty in the second minute.
Steven Caulker headed Gareth Bale's corner towards Dawson, Andre Pinto stuck out his right arm to block the ball, but referee Florian Meyer gave nothing.
Spurs were by far the more attacking side and Bale's pace down the left caused Seitaridis no end of trouble early on.
Dempsey fired a warning shot after 19 minutes with a wicked free-kick that flew inches wide.
The sparse crowd meant there was little atmosphere inside the huge Olympic stadium, but the home crowd sprung to their feet when Seitaridis whipped in a dangerous cross. Luckily for Spurs Lloris intercepted ahead of Toche, who had outpaced Dawson into the box.
Lazaros Christodoulopoulos then left Dawson in his wake to latch on to Quincy Owusu-Abeyie's through-ball, but once again Lloris came to the rescue.
Dawson's shortcomings at the back were soon forgotten, however, as he went up the other end and glanced Huddlestone's cross in to the far corner of the Panathinaikos goal.
Orestis Karnezis then saved twice in quick succession from Huddlestone and Bale as Spurs stepped up their search for a second.
Dempsey thought he should have had a penalty just before the break after going down in the box, but again Meyer said "no".
Ibrahim Sissoko would have scored within 10 minutes of his half-time introduction had it not been for an excellent tackle from Kyle Walker as the Greeks started the second period well.
Quincy beat Walker again and put in a dangerous cross that Dawson steered behind when Lloris was well-positioned to gather.
Defoe blazed over from 12 yards following a clever pass from Dempsey, Bale's swerving shot just sneaked past a diving Karnezis, before Defoe went close again with a deflected shot with 18 minutes remaining.
Spurs looked set to cruise to victory, but the hosts had other ideas.
With 13 minutes left, Seitaridis slipped past Caulker and played a brilliant through-ball to Toche, who stroked the ball past Lloris having left Dawson behind him.
The goal livened up the home crowd and their team poured forward, Caulker putting in a vital block to deny them a second goal.
Villas-Boas shared a warm embrace with opposite number Jesualdo Ferreira at the final whistle, but the Portuguese will have justification for being unhappy on the inside after seeing his team come away with only a point.