Defending champion Mark Selby was forced to fight for victory in his opening Masters match, while John Higgins also won on the first day of Masters action.
Selby edged out a battling Mark Davis 6-5 at Alexandra Palace.
The 30-year-old from Leicester saw off fellow Englishman Davis in a cagey 55-minute final frame after the 41-year-old drew the match level at 5-5 following two half-century breaks.
However, Selby, who has won the prestigious invitational event three times - in 2008, 2010 and last year - came through following a tense safety exchange to sink a red in the middle pocket and book his place in the quarter-finals.
Selby cruised to a 4-0 lead with breaks of 59 and 80 in the opening two frames, before Davis hit back after the mid-session interval to pull a frame back with a break of 80.
Davis then claimed the sixth but Selby pounced on a missed red in the next to take the best-of-11 match to 5-2 in his favour.
A break of 136 earned Davis the accolade of scoring the first century knock in the tournament and also claimed the eighth frame, and he scrapped out the next with a 49 clearance to move to within one of the defending champion.
Davis showed why he is nicknamed The Battler from Hastings when he took command of the tenth frame with a break of 62, before putting Selby to the sword with a 61 clearance after a mistake by the world number one.
That set up a tense decider which lasted just short of an hour due to missed pots and a lengthy safety battle, but Selby rallied to claim victory.
If he goes on to defend his Masters title, which is played for by the world's top 16 players, Selby will become only the fourth man to do so.
Meanwhile, John Higgins overcame Stuart Bingham in the evening game.
Higgins hit breaks of 50, 94, 65 and 109 on his way to a 5-1 lead.
Bingham did hit back with a break of 91, but Higgins wrapped up the next to make it 6-2 and progress to the last eight.