BALTIMORE -- Opposing managers concede that no lead is safe against the Baltimore Orioles' powerful lineup.

That proved to be a wise assessment once again.

Mark Trumbo hit the game-winning RBI single off Wade LeBlanc in the 10th inning, leading Baltimore past the Pittsburgh Pirates 6-5 in the opener of their two-game series Tuesday night.

"We didn't have much going," Trumbo said. "It happened pretty quick and when you get against these top relievers it's rare. We just did a really nice job tonight."

Jonathan Schoop tied the game for Baltimore with a two-run homer off Pirates closer Tony Watson in the ninth. It was Schoop's second home run of the game and 10th of the season.

"Jon watches how people are pitching him and what he's (doing) wrong and he makes adjustments to patterns and what they're doing," Orioles manager Buck Showalter said. "It's one of the challenges of playing a team you see hardly ever."

Adam Jones singled with one out in the 10th and took second on a long fly out by Manny Machado. Trumbo then delivered a liner to center field off LeBlanc (3-1).

Brad Brach (1-1) threw a scoreless inning to pick up the win. The Orioles improved to 8-1 in extra innings.

"They just beat us," Pittsburgh manager Clint Hurdle said. "We went with our strengths and they came back and won late."

Pittsburgh starter Ivan Nova was cruising until the seventh inning, when he allowed back-to-back homers to Chris Davis and Schoop that pulled the Orioles to within 4-3. Nova was forced to leave the game with left knee inflammation and is listed as day-to-day.

Nova allowed three runs on five hits with four strikeouts and a walk in six-plus innings. He has gone at least six innings in each of his 12 starts this season. Nova said the knee injury was not the reason for the home runs.

"They have a really heavy hitting lineup, especially with the big right handers," Nova said. "You have to be really careful with them. The first homer, I just stayed up in the zone. I thought it was a good pitch. The other was a high curve and he still hit it out. You have to be careful with those guys."

David Freese got his sixth homer of the season for the Pirates to provide an early 4-1 lead.

The Orioles' Kevin Gausman struggled with his command early but managed to throw 6 2/3 innings. He allowed four runs on eight hits with four strikeouts and a walk on 113 pitches.

"I think that's a theme for me, really, this whole season is giving up way too many two-strike hits," Gausman said. "I threw some great pitches to get to that point, but obviously, they also did a really good job with some fastballs up and just kind of didn't hit them hard, but just kind of hit them where guys weren't."

One of the keys for Pittsburgh this series is keeping the ball in Camden Yards. The Orioles entered the game sixth in the American League with 76 home runs, but 12th in runs scored with 244.

That became troublesome when Seth Smith drove Nova's third pitch of the game over the center field fence. The Pirates responded with four consecutive hits off Gausman in the second and took a 2-1 lead on a single by Andrew McCutchen and a double by John Jaso. A fielder's choice by Jordy Mercer provided a two-run cushion later that inning.

NOTES: The Orioles purchased the contract of INF Ruben Tejada from Triple-A Norfolk. Over 616 major league games, Tejada has hit .252 with 104, doubles, 10 homers and 253 RBIs. INF Paul Janish was designated for assignment. ... Pirates RHP Jameson Taillon (testicular cancer) will make a rehab start Wednesday for Triple-A Indianapolis. ... Orioles C Welington Castillo (groin) took batting practice Tuesday. If there are no setbacks, Castillo could be activated from the disabled list Saturday.