(Photo credit: Brett Davis-Imagn Images)

The Arizona Diamondbacks are slipping out of the playoff race and will attempt to gain some traction when they hit the road to face the surging Pittsburgh Pirates in the opener of a three-game series Friday.

The Diamondbacks came away empty-handed during a three-game series against the Houston Astros, after returning from the All-Star break with three consecutive victories over the St. Louis Cardinals.

Arizona will turn to right-hander Ryne Nelson (6-2, 3.52 ERA) on Friday, opposite Pittsburgh rookie right-hander Mike Burrows (1-3, 4.70).

The Pirates are not in postseason contention and are likely to be sellers approaching the July 31 trade deadline. But there have been some bright spots of late, including a surge from their often-anemic offense during their three-game sweep this week of the American League Central-leading Detroit Tigers.

The Pirates have been especially dangerous at home, where they have won 10 of their past 13 games.

Pittsburgh first baseman Spencer Horwitz posted a pair of three-hit games in the team's first two wins over Detroit. On Wednesday, he hit his first career grand slam in a 6-1 win. He was batting .225 when the series started after opening the month with a .258 average.

'I don't know that it's been that bad,' Horwitz said. 'I think the underlying numbers have been pretty good. But yeah, I'm getting the outward results. And I think it's rewarding, for sure.'

Arizona had high expectations when the season began, but a disappointing first half has brought uncertainty as the trade deadline approaches.

'It's kind of weird. I might say goodbye to some players on the road and I'll never see them in this clubhouse again,' Arizona manager Torey Lovullo said after the team's 4-3 loss to Houston on Wednesday. 'It initially grabs you and postures you a little bit, but we've been hardened by this game, and we know that it's a possibility and we'll figure a way out of it. We'll be fine no matter what happens.'

The Pirates took two of three games from the Diamondbacks in Arizona from May 26-28. Nelson started the lone Diamondbacks victory in that series, tossing 6 2/3 shutout innings on four hits and no walks with four strikeouts.

Nelson, who is 1-0 with a 3.09 ERA in two career starts against Pittsburgh, has done his part during Arizona's search for consistency. Since moving to the rotation full-time on June 7, Nelson is 4-1 with a 3.61 ERA and has 34 strikeouts over 42 1/3 innings.

Nelson won his most recent outing over the Cardinals on Saturday, after he allowed one run on four hits and one walk while striking out four over six innings. The Diamondbacks have won six of Nelson's past seven starts.

Burrows' first career start against Arizona didn't go well, as he gave up five runs (four earned) on five hits over 3 1/3 innings on May 27. But Pittsburgh rallied for a 9-6 victory.

In Burrows' most recent outing, he allowed two runs on three hits, walked two and struck out six over five innings during a 10-4 loss to the Chicago White Sox on Saturday.

--Field Level Media