Mast, whose best finish of the season was a tie for 15th place at the Boeing Classic on Aug. 25, shot a 3-under 69 on Friday to grab the first-round lead at the $1.6 million Montreal Championship.
The 62-year-old native of Ohio opened with three straight birdies on a windy day at Vallee du Richelieu that saw gusts up to 50 kilometres per hour on the Rouville Course.
"That's always a good start," Mast said. "I three-putted the fourth and then the wind started getting heavier. I think we got a little bit of a break playing second off. It was windy, but not as windy as it is right now. I got a chance to play four or five holes without a real heavy wind and that's already an advantage. You never know when you are going to get a break, but I think I did."
It is the first time Mast has had an outright lead in 165 Champions Tour starts. The last time he led outright in a PGA-sponsored event was at the 1993 Southwestern Bell Colonial.
"I played pretty solid," Mast said. "I'm usually a pretty good wind player. It's hard. You've got to control your ball in the wind. You've got to have a good short game. I made some key putts here and there to keep the momentum going so all of a sudden 3 under is a decent round."
Kenny Perry finished one stroke back with a 70. Perry, who holds a commanding lead over Bernhard Langer in the Charles Schwab Cup standings, fired three straight birdies on the 14th, 15th and 16th holes to finish 2 under.
"Interesting day," said Perry. "I got off to a good start but I wasn't making any birdies. I was hitting the ball nicely and that wind was very difficult."
Perry has five top-three finishes this season, including senior major wins at the Constellation Senior Players Championship and the U.S. Senior Open.
"People have been wonderful here," said Perry, who made his first appearance at the Montreal Championship, which debuted in 2010. "I feel like a rock star. I mean, I've had so much attention paid to me since I've been here. It's been amazing. I've really enjoyed it. I'm looking forward to getting out there this weekend."
Langer bogeyed the No. 18 to drop back into a four-way tie for third with a 71. The two-time Masters champion has 1,830 points for second place in Charles Schwab Cup standings, behind Perry's 2,619 points.
Mark Brooks, Mike Reid and Tom Pernice are also tied for third at 1 under.
Rocco Mediate, who recorded his second Champions Tour win Sunday at the inaugural Shaw Charity Classic in Calgary, had six bogeys on his way to a 3-over 75.
Rod Spittle of Niagara Falls, Ont., shot a 72 for the best finish of the three Canadians in the field. He is in a eight-way tie for eighth place.
Victoria's Jim Rutledge shot a 76, while Marc Girouard of Saint-Sauveur, Que., had four double-bogeys to finish with a 78.