Former champion Phil Taylor was again forced to work hard before beating Mark Walsh and moving into the last 16 at the PDC World Darts Championship.
Taylor was far from his best but still came through a tough encounter
"The Power", who also struggled against Michael van Gerwen in the opening round, had to come from 3-2 down before finally prevailing 4-3.
But the 13-time world champion showed his class to break Walsh's throw in the opening leg of the seventh set.
He held his nerve after that to seal victory with a 95 checkout.
But Taylor admitted afterwards he is yet to find anything like his best form at Alexandra Palace.
"Something's wrong somewhere. It was a strange game, I always give 150%, I was trying everything," he said.
"You practice all year round and all of a sudden you get on that stage and don't feel right."
Walsh was left to rue a missed opportunity to cause a major upset.
"When I went 3-2 up I really thought I had him," he said. "Unfortunately I didn't play too well in the last two sets and Phil did what he does."
Taylor will next meet Alan Tabern after the St Helens player beat last year's semi-finalist Andy Jenkins 4-0.
Although Jenkins won the opening leg, Tabern took control after that, winning the next 10 legs to help him to victory.
Three-time runner-up Peter Manley also advanced with a 4-1 win over Alan Warriner-Little and will play Dutchman Jan van der Rassel in the last 16.
The turning point for Manley came in the final leg of the fourth set where he hit a 96 checkout after Warriner-Little miscounted earlier in the leg when he tried to set up a finish.
Van der Rassel, who beat former world number one Colin Lloyd in the opening round, added to his scalps with a 4-1 success over Denis Ovens.
There was also victory for Dutchman Roland Scholten who piled on the pressure late on to beat Mervyn King 4-2.
The players were tied at 2-2 but Scholten kept his composure over the final two sets to set up a meeting with Wayne Mardle, who came through comfortably 4-1 against Jamie Caven in the evening's final game.
The tournament now takes a break over Christmas before resuming on Boxing Day.