Blue Jays slugger Josh Donaldson left Thursday night's 2-1 loss to the Baltimore Orioles in the sixth inning after reinjuring his sore right calf .
Donaldson, who started at DH for the second straight game, was injured as he rounded first base on an RBI double off Baltimore's Kevin Gausman. Donaldson hobbled into second base and was immediately replaced by pinch runner Jarrod Saltalamacchia.
Jays skipper John Gibbons said Donaldson will be evaluated further Friday.
Donaldson left Sunday's game at Tampa Bay after running out a ground ball. After Monday's off day, he was held out of the starting lineup for Tuesday's loss to Milwaukee, but appeared as a pinch hitter.
The 2015 AL MVP is batting .310 with two homers and four RBIs.
Donaldson also dealt with right calf soreness during spring training.
Toronto has lost five straight and is off to a franchise-worst 1-7 start.
The Associated Press contributed to this report.