After recording just one birdie on the front nine, Mediate carded three birdies and two eagles over his final nine holes to shoot a course record 8-under 63 in the opening round of the Shaw Charity Classic.
"I didn't realize I shot that low on the back," said Mediate, who shot an impressive score of 29 on the back nine, which included eagles on both the 15th and 18th holes. "I changed something up with putting today, just had Martin line me up because I hadn't made a lot for a while. Today, he lined me up and I made a lot of putts. We'll stick with that for a while I think."
Mediate sunk a 15-footer for eagle on the final hole to leapfrog past both Rod Spittle of Niagara Falls, Ont., and Bart Bryant, who both shot early rounds of 64.
"I didn't notice that," said Mediate, while adding that it's "fantastic" to see a Canadian in contention at the inaugural Champions Tour event at Canyon Meadows. "It's just good to hop over people; it doesn't matter where they're from."
Spittle had a hot start to his round with birdies on the first and third holes. He finished with three more birdies and one eagle over his final 15 holes to take the early clubhouse lead along with his playing partner Bryant.
"Obviously it was a very solid day and again it just started great right from the start," Spittle said. "I drove it in the fairway all day, hit a whole bunch of greens and I hope to be equally as boring the next couple days so we can chat again."
Spittle said he was pleased to be in contention at the event, which he had circled on his calendar at the start of the season.
"It just doesn't get any better than this," Spittle said. "Our tour has been looking forward to coming to Calgary obviously since the first of the year since the schedule was announced. Most of us north of the border know it's a great sports town, great hockey town, so it's a great fit for this tour."
Bryant birdied three of his final four holes, including the Par 5 18th, to jump into a tie with Spittle.
"I had a little bonus by making about a 20-footer on the last hole," Bryant said. "I didn't play the hole very well, but was able to make a birdie so that was kind of a bonus."
Bryant, a Champions Tour rookie, said he enjoyed getting the chance to play his round with Spittle, one of the crowd favourites.
"He got off to a real good start and I kind of caught up with him," Bryant said. "He kind of made a couple more birdies and I kind of caught up with him again. Watching him play good golf, roll in a couple putts, hit good shots, I think we fed off each other to some degree."
Jeff Sluman and Bobby Clampett also shot 64 to sit in a four-way tie for second with Spittle and Bryant.
Michael Allen, Sandy Lyle, Scott Hoch, David Frost and Craig Stadler all shot 65 to sit in a five-way tie for sixth spot.
"The great thing about this tournament and this golf course, I think there will be 15 or 20 guys with a chance to win on Sunday," said Allen, who has his sights set on carding another good round on Saturday . "You want to get out and make some birdies and keep going right now."
Although he finished at even par, Gene Jones had the shot of the day when he aced the par 3, 14th hole with a nine iron from 152-yards out.
"I never saw it go in, believe it or not," Jones said. "It came at a crucial time because it got me back to even par for the day. It's a momentum changer. You at least think you're still in the tournament."
Dave Barr of Kelowna, B.C., also shot even par on the 7,117-yard, par-71 course.
"Overall, I drove the ball quite well," said Barr, who received a sponsor's exemption to play in the tournament. "I missed a couple fairways. For being gone for three years, the butterflies were there and the nerves a little shaky on a few putts. The big key around here is keeping the ball in the fairway."
Meanwhile, Jim Rutledge of Victoria, B.C., finished well back of the leaders after shooting a two-over 73.
"To be honest with you, over the last four weeks, I haven't been hitting the ball very good and today I finally started to hit the ball better, so I'm pleased with that," said Rutledge, who birdied three holes, but also bogeyed five others. "Overall, the outcome is not so good — a couple three putts — but I struck the ball better and I hadn't done that for a month or so, so hopefully there's something good at the end of the tunnel here."