PITTSBURGH (AP) — On the day he learned the San Diego Padres would go to a six-man rotation to help limit his innings, Christian Friedrich wished he'd been able to stick around a little longer.

Friedrich gave up four runs and nine hits in six innings Thursday and the Padres lost to the Pittsburgh Pirates 4-0.

The Padres said Clayton Richard will join the rotation on Sunday. San Diego is in a stretch of 16 consecutive games and wants to keep down the workload of Friedrich (4-8), who threw only 58 1/3 innings in 2015, and 23-year-old Luis Perdomo.

The Padres are contemplating shutting down Friedrich entirely at some point in the future.

"He's a guy that we're very aware of his innings right now," manager Andy Green said. "We're looking at the health of the starters with pre-eminent importance right now."

"With Christian, we've talked openly with him that we're not sure how many more starts he has. I'm comfortable right now just kind of playing it start-by-start," he said. "He feels fine, but when you get over 40 innings above what you were the year before and you're approaching as many you've thrown at any point in time, as an organization, we have to be cognizant of that and put his health at the top of the list."

Josh Harrison hit a leadoff double in the first off Friedrich and scored on David Freese's single.

Freese hit an RBI double in the third and scored on a single by Gregory Polanco. Harrison singled home a run in the fourth.

"Similar to last start, just a couple bad pitches," Friedrich said. "The fastball (to Freese) was supposed to be down and away and I just left it up."

"I felt pretty good, just would be happier trying to go deeper into games, obviously, and would like to knock out some of those big-run innings," he said.

The Padres couldn't do much against Pirates rookie Jameson Taillon (3-2), who held them to three hits in his eight innings.

Neftali Feliz and Tony Watson combined to pitch a scoreless ninth, with Watson earning his fourth save.

UP NEXT

Padres: Paul Clemens (1-2, 4.61 ERA) will make his third straight turn in the rotation as the Padres begin a three-game series in New York against the Mets. He has not pitched more than five innings in any appearance this season.

Pirates: Ivan Nova (8-6, 4.83) will make his second NL since coming over from the New York Yankees at the trade deadline as the Pirates start a three-game series at the Los Angeles Dodgers. He gave up three runs in seven innings in his first start with Pittsburgh on Sunday.