World number one Mark Selby reached the last eight of the Masters at Alexandra Palace with a 6-4 win over Stephen Lee.
Selby, 28, looked in top form as he opened up a 5-1 lead over Lee in the best-of-11-frames contest.
But Lee came back to close the gap to 5-4 before a break of 71 secured Selby's place in the quarter-finals.
Former world champion Graeme Dott was 3-2 down to Ali Carter but had breaks of 71 and 56 in winning four successive frames to seal a 6-3 victory.
A relieved Selby, who will now face former world champion Shaun Murphy in the last eight, said: "I just seemed to lose a bit of focus, maybe because I had quite a big lead."
The Leicester-based player has won the Masters twice before and made breaks of 66, 57, 110 and 72 in establishing a four-frame lead.
He then missed an awkward red with the chance to seal a 6-1 win, and Lee knocked in a superb break of 78, followed by 94 in the next frame to cut his arrears to 5-3.
Selby had another chance to finish it in the next frame but fouled the brown to allow Lee to clear, before Selby finally booked his place in the quarter-finals.
"I probably should have won 6-1, but full credit to Stephen, he started playing well and got more and more confidence," Selby said.
"At 5-4 it could have gone either way.
"At the UK Championship I didn't perform brilliantly and lost to Marco Fu, and coming here I had that in the back of my mind. We only have a few BBC tournaments and everyone wants to produce their best snooker on the BBC.
"I've known Shaun Murphy since I was 14 or 15 and we always say it would be nice to play each other in a big final one day. It will be a good game and I need to play a lot better.
"Shaun's a great player, a former world and UK champion, and he's a great front-runner as well so if he gets on top of me early he will be hard to catch."
Dott, making his 10th Masters appearance, has never previously reached the quarter-finals, but booked a meeting against fellow Scotsman John Higgins on Thursday with a typically gritty performance.
He was behind after losing a 34-minute fifth frame following a poor safety shot on the final black.
After his break of 71 levelled the match, Dott won a tight seventh frame on the colours to take the lead for the first time.
A break of 56 put him 5-3 up and he came from 23-0 down in the next to seal his progress.
"It was a bit of a slog but my safety was pretty good. It was more a tactical game than anything else and my positional play was awful. That's the only thing I could be annoyed about," Dott said.
Looking ahead to Thursday's match the world number seven added: "When you play John Higgins you know you need to play well, my positional play can't be as bad as that. Even if John plays badly his standard is still high. I like playing all the best players, so I'm looking forward to it.
"I know I need to play really well to have a chance of winning. Sometimes that can be better than playing somebody lower ranked, when in the back of your mind you're thinking 'if he doesn't play well I might still win.' You don't get that with John."