Mark Allen overcame Nigel Bond's stubborn resistance to progress into the third round of the Welsh Open at Celtic Manor.
The world No.10 started fluently, reeling off a 93 break, but had to dig in thereafter during a topsy-turvy encounter with a player ranked 57 places beneath him.
Bond went 2-1 up before Allen hit back to take the next three largely cagey frames and extend his stay in Newport.
Allen, who felt Monday's first-round win over Fraser Patrick was the worst he has played this season, will take on the winner of last night's late finish between Scott Donaldson and Gerard Greene in round three.
Jordan Brown will play Alexander Ursenbacher after holding his nerve to beat Sam Craigie 4-3.
Brown didn't drop a frame in his first-round win over Luo Honghao but faced a sterner test against the world No.51.
A half-century in the decider sealed Brown's progress and the Antrim Ferrari admitted breathing a sigh of relief after sealing his place in round three.
"We both missed reds we should have potted in the decider and I nearly threw it away, so I'm glad to get through," he said.
"A couple of misses affected me a bit and I put a bit of pressure on myself, but it's just relief more than anything.
"I've only played Alex once before and won pretty comfortably but he showed what he was capable of by beating Ronnie in the UK Championships.
"I fancied going deep again off the back of getting to the German Masters quarters and I feel my game is in the best place it's ever been, so it's all good."
Today's action sees 32 players whittled down to eight as both the third and fourth rounds take place. Reigning champion Shaun Murphy takes on Snooker Shootout winner Ryan Day while Ronnie O'Sullivan plays Martin Gould after whitewashing his idol Jimmy White in the second round.
Mark Williams, meanwhile, believes a relaxed approach is serving him well as he goes for a third Welsh Open title.
The world No.14, who won on home soil in 1996 and 1999, eased past Liam Highfield 4-1 and plays Joe Perry today.
"I'm going for shots that are just ridiculous," he said. "I'm laughing to myself at some of the shots I'm going for. I don't care if I miss or leave them on the hole, I'm just trying to enjoy it and play as fast as I can.
"Win or lose, it's irrelevant. I'm too old now to start worrying about it."
Watch the Welsh Open live on Eurosport, Eurosport app and stream on discovery+