The Toronto Raptors came agonisingly close to securing their maiden NBA title, losing 106-105 to the Golden State Warriors.

The visiting Warriors led almost all game, until Kawhi Leonard stamped his authority during the fourth quarter with 10 straight points from his total of 26.

But Steph Curry and Klay Thompson fought back with a trio of three-pointers to wrestle the momentum. The pair finished with 31 and 26 points respectively.

Kyle Lowry then went from hero to villain in moments, taking the Raptors within one point with a driving layup with 30 seconds on the clock before badly missing a jumper that would have ensured the win.

Earlier, the Warriors' Kevin Durant left the court after falling at the start of the second quarter clutching his right calf, where an injury previously resulted in the 30-year-old being sidelined for over a month.

Golden State later confirmed that Durant would not be returning to the game and would require an MRI for a right lower leg injury.

The Raptors lead the best-of-seven series 3-2.

Golden State host game six on Thursday.