The Pittsburgh Pirates envision themselves as contenders for a playoff spot with the trade deadline on the horizon.

Sitting one game out of a wild-card spot in the National League, the Pirates will look to improve their standing at the expense of the visiting Arizona Diamondbacks on Monday in the opener of a three-game series.

Arizona has lost two in a row and is the team holding that final wild-card spot in front of Pittsburgh. Four other teams are within three games of the Diamondbacks as the major league trade deadline looms on Aug. 3.

"We have the resources to win games and be playing baseball in October," Pirates general manager Ben Cherington said. "We have to go do our jobs, and I don't think anything's changed. We believe this team is capable of doing that. We gotta continue to do the work to actually make that a reality."

Ryan O'Hearn did his part on Sunday, celebrating his 33rd birthday by belting a grand slam in an 8-7 victory over the visiting Chicago Cubs.

Esmerlyn Valdez launched his 14th homer in 37 games and Shawn Ross also went deep for the first time while playing in his second career game.

"Amazing, especially with my family here, my mom and dad," said Ross, who is from Puerto Rico. "They come to the States (to see my play) once, I was really happy for that. Really emotional."

Brandon Lowe collected three hits and scored two runs in the win. He went 5-for-9 with two solo homers to help Pittsburgh win two of the three meetings against Arizona in early May.

The Pirates will send Mitch Keller (6-7, 4.90 ERA) to the mound on Monday against the Diamondbacks' Merrill Kelly (8-8, 5.12) in a battle of right-handers.

Keller struggled in his first two starts in July before scattering three hits over five scoreless innings on Wednesday, albeit in a no-decision against the New York Yankees.

"I'm trending in the right direction," Keller said. "I don't think I have it all figured out yet but a lot of positives, for sure."

Keller, 30, picked up the win in his last encounter against Arizona, yielding two runs on four hits in six innings of a 4-2 win on May 7. He is 2-0 with a 2.29 ERA in six career appearances (all starts) versus the Diamondbacks.

Kelly answered a five-start losing streak in June by going 3-0 with a 2.45 ERA thus far in July. He permitted two runs on five hits in five innings of a 15-5 victory over the Athletics on Wednesday.

"Hopefully, we can take the momentum of the baseball we've been playing at home and take it on the road and squeak out some wins," Kelly said. "That way we can put ourselves in a good place to be on the right side of the ball for the deadline."

Kelly, 37, is 3-1 with a 3.14 ERA in five career appearances (all starts) against the Pirates.

Geraldo Perdomo and Ketel Marte each belted a solo homer and Gabriel Moreno drove in a pair of runs in Arizona's 10-7 setback to the Washington Nationals on Sunday.

--Field Level Media