Aug 13 (Reuters) - Roger Federer survived an opening-match fright by outlasting Canada's Vasek Pospisil 7-6 (4) 5-7 6-2 on Wednesday to claim his 300th Masters Series win and reach the third round of the Western and Southern Open in Cincinnati.
Back in action after losing to Jo-Wilfried Tsonga in the final of the Rogers Cup in Toronto on Sunday, third-ranked Federer appeared sluggish at times as he struggled to tame the 46th-ranked Canadian.
With the victory the second seeded Swiss, a five-time champion on the Cincinnati hard courts, becomes the first player to reach 300 wins in the ATP Tour's elite Masters 1000 events.
The match began with a tight opening set that saw neither player able to capitalise on break chances, Federer eventually winning the tiebreak on a forehand error by the Canadian.
Pospisil, winner of the Wimbledon doubles title with American Jack Sock, battled back to take the second but a focused Federer wasted no time taking charge in the third with an early break on way to clinching the milestone win.
The day featured a pair of early upsets with Taiwan's Lu Yen-hsun shocking fourth seeded Czech Tomas Berdych 3-6 6-3 6-4 while Poland's Jerzy Janowicz knocked off Bulgarian seventh seed Grigor Dimitrov 6-4 3-6 6-3.
After a first round bye eighth seeded Briton Andy Murray got his tournament off to a convincing start easing past Portugal's Joao Sousa 6-3 6-3.
Murray, who has twice hoisted the trophy in Cincinnati, faced just two break points the entire match saving both while disposing of his Portuguese opponent in a tidy 72 minutes.
"The conditions are completely different here to Toronto," said Murray, who made a quarterfinal exit in Canada. "A few of the guys that have come in late have struggled with the conditions.
"I hit the ball well from the back of the court today. I was able to control the ball well.
"That was, for me, the most pleasing thing about the match today because I have seen a lot of the players have struggled so far.
Top-ranked American and 11th seed John Isner blasted his way into the third round firing 16 aces on way to 6-3 7-6 (1) win over Australian qualifier Marinko Matosevic. (Reporting by Steve Keating in Toronto; Editing by Frank Pingue)