The Blue Jays right-hander gave up six runs in two-thirds of an inning before he was taken out of the game in Toronto's 14-3 loss to the Texas Rangers. Morrow cut off his postgame interview after taking only one question.
"I'm just going to pretend that that game never happened," said Morrow, who had thrown two shutouts in his previous four starts.
Nelson Cruz hit a grand slam and tied his career high with eight RBIs, Josh Hamilton hit his 19th home run of the season before leaving with a head cold and the Rangers broke out of an offensive slump with 18 hits.
Coming off a three-hit shutout against the New York Mets last Saturday, Morrow didn't even get out of the first in the shortest start of his career. But he wasn't the only pitcher who struggled for the Blue Jays, who lost their third straight. The next three relievers gave up eight runs in 6 1-3 innings.
After stretching his bullpen in an 11-inning loss to Tampa Bay on Wednesday, manager John Farrell elected to send backup catcher Jeff Mathis to the mound in the eighth.
Mathis pitched a scoreless eighth, becoming the sixth position player in Toronto history to pitch. The Rangers had a double and a walk against Mathis before Alberto Gonzalez flied out to end Mathis' night on the mound. He was the only Toronto pitcher not to give up a run.
Mathis said he hadn't pitched in a game since high school.
"(Farrell) asked me and I'd done it before," Mathis said. "Any way I can help the team out."
The Rangers are the top-scoring team in baseball despite averaging 3.5 runs over their previous 10 games. Texas was held to seven runs in dropping two of three to Seattle earlier in the week.
Cruz had a three-run double in a six-run first, then capped his big night with a 414-foot grand slam that landed in the upper deck in right.
"You dream to have those kinds of days," said Cruz, who also had an RBI single in the sixth and went 4 for 5. "It can't happen every day. When it happens, you should be happy and enjoy it."
Cruz also drove in eight runs against Toronto on July 22, 2011. His grand slam in the seventh was the fourth of his career and second of the season.
Cruz is the sixth players in Rangers history to drive in eight or more runs in a game. Ivan Rodriguez has the Rangers team record with nine on April 13, 1999, against Seattle.
Morrow's ERA jumped from 2.63 to 3.47 after he gave up five hits and three walks in a 44-pitch outing. He faced 10 batters before he was relieved by Carlos Villanueva.
"He's had a very strong year for us," Farrell said. "I'd like to think this is the aberration. He's been extremely dominant in many cases so far this year. He'll be back out there Wednesday."
Derek Holland (4-3) struck out a season-high nine in 7 1-3 innings. He allowed two runs and five hits.
Hamilton, who leads the majors in home runs, had gone 11 games without a homer before leading off the second with his first since May 12. He left the game in the seventh inning.
Yorvit Torrealba added his first home run, and Adrian Beltre and Michael Young each had three hits.
"To win in this league, you have to play a complete game," Texas second baseman Ian Kinsler said. "It was nice to break out like this."
Beltre had a two-run single and Cruz's bases-loaded double gave the Rangers a 5-0 lead.
Mitch Moreland's RBI single capped the scoring in the first, and Morrow was relieved one batter later after Kinsler doubled to centre.
Hamilton's home run leading off the second landed in the second deck in right and gave him 50 RBIs this season. He became first player in club history to hit 19 home runs in the team's 46 games of the season.
Toronto's Edwin Encarnacion hit his 15th home run and Jose Bautista had a two-run single.
NOTES: Mathis was the first Blue Jays position player to pitch since Mike McCoy last June. ... Rangers C Mike Napoli was held out of the lineup with an upset stomach. ... Hamilton tied the club record with his 10th home run in May. ... Toronto 2B Kelly Johnson singled in the third to reach base in his 19th straight game. ... Pro golfer Jason Dufner threw out the first pitch. Dufner leads the Colonial, which is being played in nearby Fort Worth, after two rounds.