PHILADELPHIA -- On the first two nights of the Nationals¡¯ four-game series at Citizens Bank Park, starting left-handers Mitchell Parker and Patrick Corbin combined for 7 1/3 innings against the Phillies.

Between Thursday and Friday¡¯s losses, Eduardo Salazar, Tanner Rainey, Orlando Ribalta and Jacob Barnes pitched one-plus innings out of the bullpen. Robert Garcia, Derek Law and Kyle Finnegan made relief appearances as well.

¡°We¡¯re using our bullpen a lot,¡± manager Dave Martinez said.

Corbin still is pursuing his 100th career win after his pitch count rose to 96 over 4 1/3 innings on Friday in the 3-2 walk-off loss. He gave up two runs off two hits and two walks with two strikeouts. Corbin is 1-5 at Citizens Bank Park in nine career starts.

¡°They fouled a lot of balls off,¡± said Martinez. ¡°He was in a lot of 3-2 counts. ¡­ That¡¯s what those guys do.¡±

Corbin, who ranks second on the Nats to Jake Irvin in innings pitched (135 1/3 over 25 starts), has gone less than five frames in three of his last four outings.

¡°They¡¯re a tough lineup over there,¡± Corbin said. ¡°You try to make pitches. Sometimes against a team like this, you¡¯re maybe trying to get through five and keep your team in the game. I think early on, when the pitch count got up, that was kind of on my mind to do that. I wasn¡¯t able to get out of that fifth there.¡±

Parker entered the series having pitched 12 1/3 frames with only two unearned runs allowed over his last two starts, but facing the Phillies for the first time in his career on Thursday, the rookie allowed nine runs off 10 hits -- including two homers -- and two walks in the 13-3 loss.

¡°Obviously, we know the guys that they have and know what they can do,¡± said Parker. ¡°At the end of the day, attack and try to limit the damage, which sometimes is a little hard to do.¡±

While Weston Wilson recorded a triple off Parker en route to hitting for the cycle on Thursday, Parker viewed the entire lineup as an offensive threat. That was exemplified on Friday when former National Trea Turner belted a walk-off single off the left-field wall against All-Star closer Kyle Finnegan.

¡°They all have really good at-bats, they swing it real well, they get the pitch that they want,¡± Parker said. ¡°They¡¯re all kind of the same -- they get what they want.¡±

The Nationals will look for a bounce-back performance on Saturday by MacKenzie Gore, who has not completed six innings since June 14. Although Gore did not allow any earned runs in his last start on Sunday, he issued six walks and surrendered five unearned runs.

¡°It¡¯s all about consistent strikes, getting the ball over the plate,¡± Martinez said after Gore threw his bullpen session on Wednesday. ¡°We talked about his usage and different pitches. I know he¡¯s going to compete, as he always does. But it¡¯s about pitch efficiency with him and trying to get him to throw more strikes.

¡°We still feel like we¡¯re doing OK. We¡¯ve got some days off coming up. We¡¯ll revisit that, for sure. I know we talk about it a lot, so we¡¯ll definitely revisit that soon.¡±

The Nationals could expand to a six-man rotation as they did toward the end of last season. Before doing so, however, the team wants to continue to build up the workload of their young starters, such as Parker and fellow rookie DJ Herz, to prepare for the future.

¡°It¡¯s another part of the process where we want to make sure they get enough innings so that when we add that 20, 25 percent next year and we¡¯re playing in September for really something, that they¡¯re able to continue to help us win games,¡± Martinez said pre-game. ¡°We¡¯ll reevaluate everything here probably in another week or so after we get through this week with the day off [Monday], and then we¡¯ll go from there.¡±