Selby had blown away Ronnie O’Sullivan 6-0 in the quarter-finals, but managed to pot just one red as Zhang produced a superb run to head into the mid-session interval with a seemingly commanding 4-0 lead.
Zhang, who beat veteran John Higgins in the last round, had opened up with a fine 129 clearance.
The tournament’s third seed then reeled off runs of 80, 69 and 84 to leave Selby stuck in his chair and in need of inspiration during the interval.
It looked to remain one-way traffic after the restart as Zhang built break of 56 before missing a black into the right corner, which allowed Selby to the table to pot his first ball in almost 45 minutes and he went on to claim the frame with a measured clearance of 62.
Selby, a four-time world champion, produced another carefully crafted break of 85 to further reduce the deficit at 4-2.
The seventh frame proved a much tenser affair, with Selby having initially made headway before running out of position. After an exchange of safety play, Selby slipped a key red into the middle followed by another couple with colours which was enough to pull another frame back.
Selby had an opportunity to level the match in the next frame, but a poor safety attempt allowed Zhang back with the table well set. He eventually ground out the frame 64-40 after more than 45 minutes to move one away from victory.
Zhang, though, then missed a straightforward red into bottom right pocket to gift Selby an opening, which he took with a fine century break of 113 to claw another frame back at 5-4.
Selby opened the 10th frame with break of 51 before leaving the door open for Zhang, but he could not push through it, missing the final brown as Selby forced a deciding frame.
It was only a temporary reprieve, however, as Zhang hit an early break of 50 in the decider, which proved enough to advance to the final against Mark Allen.
