PITTSBURGH -- Coming off a series in which they scored just three runs, the Pittsburgh Pirates used the long ball to jump out to a big lead early and held on for a 6-3 victory over the New York Yankees in interleague play Friday night.

The Pirates scored two runs in each of the first two innings, quickly eclipsing their total from the previous three games. The Pirates knew they would need a better offensive performance on Friday with rookie Tyler Glasnow on the mound. Glasnow had struggled through his first two starts and was carrying a 12.15 ERA.

They were able to accomplish that goal from the very first batter, as Jordy Mercer hit a leadoff home run to the batter's eye in center field to start the scoring in the first inning. It was Mercer's first home run of the season.

"I think it's just big for (Glasnow), and big to set the tone," Mercer said. "He's had his struggles but he's improving and I think the most important thing is each and every start, he's come out and he's improved and he's thrown strikes. Everybody knows the stuff's there. It's just a matter of refining it, and I think it helps with a four-run lead after two to be able to settle down and throw strikes."

After Mercer, it was rookie first baseman Josh Bell that hit his second home run of the season -- a two-run shot off Yankees' starter C.C. Sabathia (2-1) -- to give the Pirates (7-9) a 4-0 lead in the second inning. The home run traveled 410 feet into the left-center field notch at PNC Park and was Bell's first from the right side of the plate in the majors.

Sabathia went on to last five innings, allowing four runs on seven hits, both season highs. He also struck out three and walked two, but never felt crisp from the beginning.

"I felt pretty good, stuff was just a little short today," Sabathia said. "I tried to battle and keep the team as close as possible. ... Just didn't get a ball in enough on Bell and Mercer."

The Yankees (10-6) offense relied on some help from the Pirates' defense. In the third, an error by Osuna allowed Brett Gardner to score on Chase Headley's double. In the fifth, an error by Josh Harrison scored Jacoby Ellsbury and Aaron Judge.

All of the runs came off Pirates' starter Tyler Glasnow, though just one was earned. Glasnow was removed after 4 2/3 innings, but dropped his ERA to 7.94 on the season. Even without his best stuff, he was able to show incremental improvement.

"The timing's not there and I think he biggest thing is you just have to brush all the stuff aside and just compete," he said. "I think the last couple starts, it hasn't been -- obviously -- spectacular. But it's been coming along with each start getting a little better so just keep my head down and keep working."

Juan Nicasio (1-2) earned the win in relief. Tony Watson pitched the ninth for his fifth save.

The Yankees' defense gave two runs back with two outs in the seventh, when second baseman Starlin Castro dropped a pop up off the bat of Andrew McCutchen that scored Mercer from second. Two batters later, David Freese singled home McCutchen.

"He had to run a long way," New York manager Joe Girard said of Castro's error. "I thought he was there. He just dropped it. It's gonna happen once out of 100 times, but it's the time that happened."

Bell's round-tripper scored right fielder Jose Osuna, who had reached base with his first major-league hit on a triple to right field. Osuna, 24, had made his major-league debut Tuesday in St. Louis.

NOTES: Pirates RF Jose Osuna made his first career start. In the three games since outfielder Starling Marte received an 80-game suspension from Major League Baseball, the Pirates have started three different right fielders: Adam Frazier, John Jaso and Osuna. Manager Clint Hurdle said to expect a rotation to continue unless one player takes hold of the job. ... Yankees INF Didi Gregorious (shoulder) made his first rehab appearance, going 2-for-3 in six innings with Single-A Tampa. Gregorious was injured during the World Baseball Classic. ... Yankees LHP C.C. Sabathia went 0 for 2 at the plate. He's now on an 0-for-23 streak since June 15, 2010, but has maintained a career .214 batting average.