By ESPNSTAR.com staff
Leading 1-0 on aggregate courtesy of Samuel Ajayi's winner in last week's first leg, the Glass Rabbits edged ahead on the night in the 46th minute when the Nigerian found the back of the net once again.
Chonburi then piled the pressure on their opponents in a bid to spark off an unlikely comeback but failed to find a way past their opponents' resilient defending until the 86th minute, when veteran midfielder Therdsak Chaiman pulled one back from the spot.
Teeratep Winothai had one final chance to kill the game off for the visitors when he raced through on goal in the dying stages but he failed to score, although his side managed to hold on to book their place in the last four.
Glass will find out their semi-final opponents next week when the other three semi-final clashes are completed, with Buriram United taking on BEC Tero Sasana, Division 1 side Ratchaburi playing Wuachon United, and Muangthong United facing off against TOT.