The US right-hander, a three-time winner of the Cy Young Award as a season's top pitcher, is also unlikely to compete in the play-offs if Texas advance, Rangers general manager Chris Young said.

Scherzer has suffered a low-grade strain of his right teres major muscle, which connects the arm to the upper torso.

Scherzer, who won a World Series title in 2019 with the Washington Nationals, exited after 5 1/3 innings of a 6-3 Texas victory at Toronto on Tuesday with what had been diagnosed as a right triceps spasm.

"It started tightening up. It just felt like a charley horse," he said. "All of a sudden it's in my triceps back to my shoulder.

"When I got on the mound and was trying to go through my motion, I could just tell. I tried to get it going. I could just feel I wasn't going to be able to throw another baseball so I had to come out at that point."

The Rangers obtained Scherzer from the New York Mets just before the trade deadline and since arriving he went 4-2 with a 3.20 earned-run average and 53 strikeouts over 45 innings.

Scherzer, who has led MLB in season wins four times and National League strikeouts three times, has enjoyed an epic career since his 2008 MLB debut with Arizona. He also pitched for Detroit, Washington and the Los Angeles Dodgers before joining the Mets last year.

His loss comes as the Rangers are battling for an MLB play-off berth with just under three weeks remaining in the six-month season.

At 80-64, the Rangers are only one game behind Houston in the fight for the American League West division title.

They own the second of three American League wild-card play-off positions by half a game over division-rival Seattle and Toronto, both 80-65.