Hayes (ankle) is starting Thursday's game against the Cardinals, Kevin Gorman of TribLive.com reports.
Hayes didn't appear in any spring games after March 25 due to a minor ankle sprain, but he'll start at the hot corner and bat third during Thursday's Opening Day matchup. The 25-year-old appeared in 96 games for Pittsburgh last year and hit .257 with six homers, 49 runs, 38 RBI and nine stolen bases.