Padres manager Andy Green said he didn't have a medical update on Lamet's condition after an 11-7 loss to Seattle.
"Hopefully he's not out for long, but usually when you walk off the mound and your elbow hurts, it's not a good thing," Green said.
The 25-year-old Lamet made his fourth spring training start. He had been expected to be the second-day starter in the Padres' rotation after Clayton Richard opened Thursday at home against Milwaukee.
"He threw a slider and felt it," Green said. "It was the last or second-to-last pitch. Anytime you pull one of your main guys out of a game, at any time in spring training, it's concerning. The last tuneup outing before the season, it's very concerning. We'd love to have him, he's a big part of what we plan on doing."
Lamet exited in the top of the second inning after a pitch he threw got away for a passed ball. His start lasted 1 1/3 innings and he allowed an earned run on two hits with two strikeouts.
Last season, Lamet went 7-8 in 21 starts with a 4.57 ERA. He struck out 139 in 114 1/3 innings.
This spring, Lamet posted a 3.75 ERA in 12 innings.