(Carolyn Kaster/AP)

Lannan, the former opening day starter who spent all season at Class AAA Syracuse, fired a three-hit shutout Saturday at Gwinnett, the Braves’ affiliate. He walked one and struck out two in his start.

Lannan, 27, is the likeliest candidate to take Strasburg’s spot in the rotation when the Nationals decide he has reached his innings limit. A fixture in the Nationals’ rotation for the previous four years, Lannan was optioned to the minors on the eve of opening day this year to make room for Ross Detwiler.

Lannan has twice joined the Nationals to pitch one game of a doubleheader, and the Nationals won both of them as he allowed five earned runs over 13 innings. At Syracuse this season, Lannan has a 4.58 ERA over 139 2/3 innings.