Thomas hit two home runs to pass Eddie Murray for 20th place on the all-time home run list, and the Blue Jays beat the Texas Rangers 9-5 on Saturday.
"I really want to stay focussed and finish strong because I'm disappointed in my season so far," said Thomas, who is batting .255 with 18 homers and 60 RBI.
"I know what I'm capable of doing. It just hasn't worked out. But with two months to go, who knows? I might get on one of those hot streaks and make it a very good season."
Thomas won American League Comeback Player of the Year honors in 2006 after batting .302 with 32 homers and 94 RBI over season's final 100 games.
Toronto is fifth in the wild card race, but Thomas hasn't given up hope of a postseason berth.
"You never know where we might find each other in September," he said. "I just feel we're not out of this with the lineup we've got and the way the pitchers have been pitching. The wild card is still a possibility for this team."
Toronto came into Saturday seven games behind Detroit in the Wild Card race.
Thomas hit a three-run homer in the first and added a solo homer in the third, giving him 505 for his career. It was his second multihomer game of the season and the 31st of his career.
Thomas took pride in passing Murray, his long time friend.
"He's one of my buddies, one of the greatest of all time," he said. "It's a good feeling, a real good feeling."
Right on Thomas' heels is Alex Rodriguez, who hit his 500th home run Saturday against the Kansas City Royals.
"I saw it," Thomas said of Rodriguez's historic shot. "I'm happy for him because it's been stressful for him. Now he's probably going to take off like the rest of his season has been."
The Blue Jays extended their home winning streak to seven games, and have outscored opponents 50-14 over that span.
"The guys are confident," Thomas said. "Throughout the lineup, the guys are swinging the bats. If we keep getting the consistent pitching we've been getting the last couple of weeks, you just never know what might happen."
Shaun Marcum won his third straight start for Toronto.
Texas has dropped six of eight following a season-high four-game winning streak and lost despite out-hitting Toronto 11 to nine.
"We just didn't deliver," Texas manager Ron Washington said.
Thomas homered for the first time in eight games and ended Toronto's 66-inning homerless streak. The Blue Jays had not homered since Gregg Zaun's three-run shot in the sixth inning of a July 25 victory over Minnesota, their longest drought since a 69-inning streak in 2005.
Thomas finished 2-for-4 with four RBI, while John McDonald went 2-for-3 with three RBI.
Marcum (8-4) allowed three runs -- two earned -- on eight hits over six innings. He walked none and struck out five.
Brian Wolfe pitched a perfect seventh and Brian Tallet worked the eighth. Brandon League allowed a pinch-hit homer to Brad Wilkerson and an RBI single to Adam Melhuse in the ninth before Scott Downs got the final two outs.
Texas took a 1-0 lead in the first when, with the bases loaded, Zaun was called for catcher's interference on Nelson Cruz, who struck Zaun's glove with his bat while swinging.
"We came out in the first swinging the bats and that's a big momentum changer," Marcum said. "It took the breath right out of them."
That brought up Thomas, who homered on the first pitch he saw from Eyre (3-4).
"I'll go weeks at a time without swinging at the first pitch," Thomas said. "You never know when I might be ready to hit one. I was happy that happened. It was big for the team there."
Eyre gave up six runs and seven hits over 2 1/3 innings, walking two and striking out two.
"Willie left some balls out over the plate and the type of hitters those guys are over there, they don't miss too much," Washington said.
McDonald capped the scoring with a two-out, two-run double in the fifth off reliever Wes Littleton.
- Thomas, who became the 21st player in baseball history to hit 500 home runs on June 28 at Minnesota, is six homers from tying Mel Ott (511) for 19th place.
- With his first home run of the game, Thomas also passed Ernie Banks for sole possession of 24th on the all-time list. Thomas now has 1,639.
- Glaus and Thomas are tied for first among active players with 35 career home runs against Texas.