Bassitt has been diagnosed with a left hamstring contusion, John Hickey of the Bay Area News Group reports.
In his third Cactus League start Monday, Bassitt was less than crisp against the Giants, allowing four runs on eight hits and one walk while striking out four in 5.1 innings. Prior to the outing, he had tossed five scoreless frames with four punchouts versus two free passes, but the hamstring injury may have played a part in Monday's subpar performance. Although it's unclear if his next spring start will be skipped, a delayed return could hinder his chances of opening the season in the Athletics' rotation.