Black said he chose Marquis over the righty Ross Ohlendorf, who will assume his role as long reliever until the All-Star break. Ohlendorf was available Friday and could be a fit to relive Marquis on Sunday if needed.
Marquis' last outing came July 4 in Arizona, a no-decision in which he gave up four runs on eight hits in 6 1/3 innings. In six career starts on three days' rest, the 33-year-old is 1-2 with a 3.93 ERA.
Since being called up to San Diego on June 7, Marquis has a 3.49 ERA and a 1-4 record in six starts. He has struck out 39 batters in 38 2/3 innings of work, including a 10-strikeout showing in a June 18 loss to Texas.
Black has not yet announced whether or not he plans to reset his starting corps for the second half, which begins July 13 with a three-game set against the Dodgers in Los Angeles.
Black said he will most likely announce his pitching plans for that series on Sunday.