"I think that's something you want people to say about you," Cooper said of his clutch hits. "That's a big part of what you can do in this game and hopefully it keeps going.
"That's the situation you want to be in every time. It's the most fun part of the game right there."
Cooper came to the plate with one out and runners on the corners against Chicago right-hander Nate Jones. Cooper quickly got ahead 3-1 and eventually drove a full-count slider into right field to give Toronto its third walk-off victory.
The 25-year-old Cooper has been one of the only bright spots in what has otherwise been a struggling offensive unit in recent weeks. Overall, he is hitting .287 with four homers and 10 RBIs in 38 games and has done an admirable job of filling in for Adam Lind, who is on the disabled list with a sore back.
"It's just like anything else, you get more confidence as you go along," said Cooper, who is in his fourth stint with the big league club. "I think you get more confident and comfortable every time you keep coming back. You feel better each and every day."
The Blue Jays appeared on their way to victory earlier in the game. Janssen, who entered a perfect 15-for-15 in save opportunities since taking over the closer's role on May 9, was handed the ball in the ninth with a 2-1 lead.
Janssen had allowed a total of seven baserunners in the 15 2/3 innings while facing the minimum in all but four of those games. White Sox slugger Adam Dunn put an end to the impressive run, sending the first pitch into the bullpen in left field for his 33rd home run.
"It had the height I wanted, I didn't get it in and obviously, when you get it more in the lane, it cuts a little better," Janssen said of the mislocated pitch. "It just didn't get there."
The late-inning problems for Toronto took a victory away from Carlos Villanueva, who continued his strong run in the starting rotation with another effective outing. Villanueva allowed just one run on five hits while striking out eight to avoid losing three consecutive starts for the first time in his career.
Villanueva has gone from long reliever to arguably the Blue Jays' most reliable starting pitcher in a matter of months. Since entering the rotation on June 29, he is 4-2 with a 3.04 ERA while striking out 50 and walking just 13.
The only trouble Villanueva had during the game was a Dunn at-bat in the fourth inning. Villanueva fell behind 3-2 when he served up a thigh-high fastball that was sent above the former Windows Restaurant in right-center field. Dunn, who has 32 multi-homer games in his career, hit the ball an estimated 469 feet and tied the game at 1.
The 28-year-old Villanueva has been the model of consistency while at the same time providing a stabilizing influence on a starting staff that has been decimated by injuries. Villanueva has allowed fewer than four runs in all but one of his eight outings while also recording five quality starts.
It's possible the numbers would be even more impressive if he wasn't under such a watchful from the Blue Jays coaching staff. Toronto has opted to limit Villanueva's innings following a year in which he experienced issues with his right elbow. That was the case again on Monday night as Villanueva was pulled after seven innings despite having only thrown 85 pitches.
"I understand why they didn't want me to either," Villanueva said of potentially going back out for the eighth. "I threw over 100 last time, it was the fourth time through the order and after we got that run. We've had our late-inning relievers rested.
"I wanted to go out, I knew I didn't have that many pitches, I knew it was below 100, so I would have tried to go out there and kind of extend myself but for me, as long as I go deep, six, seven innings, we can cover that and if they feel like I've had enough, I kind of have to do what the boss says."
Rookie outfielder Moises Sierra initially gave Villanueva a chance for a victory by sending a solo shot over the wall in left-center field. Sierra's first home run of his brief Major League career came on a 1-1 pitch and spoiled what had been an impressive night on the mound by right-hander Jake Peavy.
The 23-year-old Sierra continues to impress during his audition with the big league club while Jose Bautista is on the 15-day disabled list with inflammation in his left wrist. Sierra now has 12 hits in 11 games since receiving the promotion from Triple-A Las Vegas on July 31.
"Very excited," Sierra said. "I looked for a good pitch to help my team and I'm very excited. My first home run in the big leagues. Right now, I'm swinging good and I feel comfortable."