The 29-year-old Ruf came into camp competing with former MVP Ryan Howard for regular playing time at first base.
Phillies manager Pete Mackanin has talked about platooning the two, and Tuesday's game could strengthen that standpoint: the righty-hitting Ruf's home run came off Pittsburgh lefty Jonathon Niese.
"It was a cutter," said Niese, who chatted with Ruf after reaching on a single in the third inning. "I told him when I got on first base that I'm never throwing it to him again. He's punished it every time I've thrown it to him."
Ruf has three homers and a .294 average for his career in the regular season against Niese, a former Met.
"I know I've hit a couple of home runs off him in the last couple of years," Ruf said with a laugh. "I think he's trying to get in my head."
Ruf hit .371 against left-handers last season, and his 1.107 OPS against lefties was best in the National League among players with at least 100 plate appearances.
Cesar Hernandez, who replaced Chase Utley at second base last season, doubled the Phillies lead with a two-run triple in the second inning. Hernandez, 26, took over as the team's regular at the keystone when Utley was injured in June and then traded to the Dodgers.
Howard, meanwhile, hasn't played in a game since March 4. He was sent away from camp on Saturday with a head cold that's been spreading through the Phillies clubhouse in the last two weeks.
Phillies: LHP Adam Morgan allowed just one hit in three shutout innings. Morgan, who had a 4.48 ERA in 15 starts with the team last year, entered camp as a bit of an underdog to reclaim his job in the rotation over newcomers Vince Velasquez and Brett Oberholtzer (acquired in a trade for Ken Giles) in camp. All three pitchers have thrown three scoreless innings in the last two days.
"The competition in here is just making everybody else better," Morgan said. "So for them to go out and throw three innings scoreless, that's awesome for them. We're here to make the Phillies better, so you can't really root against (them), because we're playing for the same team."
Pirates: Niese, acquired in a trade with the New York Mets this winter, allowed four runs in three innings but was encouraged after retiring each of the final five hitters he faced.
"I didn't really have my stuff out there, particularly my two-seam fastball, I couldn't locate it," he said. "I fought through it. I'm not really worried about the results, just worrying about the process, getting the volume in."
Phillies: OF Aaron Altherr will undergo surgery on his injured left wrist on Wednesday. He is expected to be out 4-6 months. ... OF/INF Cody Asche has begun hitting in his slow return from a right oblique injury. He hasn't appeared in a game yet this spring. ... RHP David Hernandez is day-to-day with right triceps tendinitis.
Pirates: RHP Gerrit Cole (right rib inflammation) will face hitters for the second time in three days on Wednesday, which should be the last test before he's ready to get into his first game this spring.
Phillies: Philadelphia has a split squad, with one game scheduled at home against the Orioles and another in Fort Myers against the Twins. Jeremy Hellickson will face fellow right-hander Yovani Gallardo in Clearwater, and right-hander Zach Eflin will face Minnesota left-hander Tommy Milone.