Hawkins set for lift-off with Rocket; SNOOKER.
Dale, trailing 11-5 overnight, claimed the first seven frames of the session to shock last-year's runner-up who needed just two further frames when play began yesterday afternoon.
He eventually got them, but they were the last two of the session as Hawkins set up a repeat of last year's final.
Dale took the first three frames of the day with breaks of 75, 65 and 64 before claiming a slightly scrappier encounter to go into the mid-session interval just two behind.
A break of 61 in the 21st made it 11-10 and the Welshman then prevailed from a long safety battle to level up the scores.
A 52 clearance in the next edged the player known as 'Spaceman' ahead and at that point it looked like momentum would carry him over the line but Hawkins is made of stern stuff and claimed his first frame of the day with a break of 66, which took the match to a decider.
Both players were edgy in the opening stages but it was Hawkins who held his nerve with a 65 clearance to go through.
Earlier in the day, O'Sullivan admitted he was surprised with the "easy" nature of his victory as he demolished Shaun Murphy 13-3 with a session to spare.
The five-time champion capitalised on a host of mistakes from his opponent, and said: "You just never know what type of match you're going to get.
"You can expect a really tough match and it turns out easy like it did with Shaun. I didn't expect to win it that easy to be fair. He's a free-scoring great potter.
"He just missed a few balls and let me in quite easily. I still had to pot them but I didn't have to fight for my chances."
Mark Selby also breezed through to the semi-finals after claiming the one remaining frame he needed against Alan McManus.
The Leicester cueman came into the session with a commanding 12-4 lead and veteran McManus won the opening frame with a break of 69 to extend the contest.
The Scot was among the balls again early in the 18th before losing position on 20, opening the door for Selby to close out a 13-5 win.