Toronto Raptors head coach Dwane Casey has praised the mental strength of his players after they came from behind to record a 103-98 victory over Oklahoma City Thunder on Wednesday night.

DeMar DeRozan led the Raptors to overturn an eight-point deficit in the final six minutes at Chesapeake Energy Arena and record their fifth straight victory to start the 2015 season.

Toronto are now the only undefeated team in the East Conference, and Casey hailed the focus of his players after the victory.

"You do not win on the road a game like we did [on Wednesday] - I do not care who you are - if you do not have some mentally tough guys that can sustain their focus and effort," Sportsnet quotes him as saying.

"We know what happened last year. We kind of let the air out of the balloon a little bit, so we cannot relax."

Raptors next face Orlando Magic this weekend.