DETROIT -- Manager Clint Hurdle used the word "tough" three times in summing up the Pittsburgh Pirates' sweep of its three-game interleague series with the Detroit Tigers.

"We played some good baseball,” Hurdle said Thursday after Pittsburgh downed Detroit 8-4 to complete its sweep behind seven innings of shutout pitching from veteran left-hander Francisco Liriano and four hits from second baseman Neil Walker.

"We pitched tough," Hurdle said. "We had some tough offense. We played tough defense."

He could have added a fourth "tough" -- that right now the Pirates are tough to beat. After a 17-9 June, Pittsburgh is 2-0 in July.

It's not who you play, Detroit's most recent two managers (Jim Leyland and Brad Ausmus) are fond of saying, it's when you play them.

Right now would be a good time to be playing Detroit, according to that measure.

"We had hoped we would get a little spark from beating the Chicago White Sox on Sunday," Ausmus said. "But four days later and we're looking at a sweep."

Liriano allowed five hits in seven shutout innings, walking three and striking out five.

"He's tough any time he takes the mound," Ausmus said of Liriano. "He's throwing more strikes now than he has in previous years. We knew coming into this series we were facing three very good pitchers."

Hurdle said, "He was throwing his fastball, curve and slider. They weren't able to sit on any one of them. And he got 11 guys out with three pitches or less."

The Pirates' bullpen had a hiccup in the eighth, though, when left-hander Antonio Bastardo allowed a three-run homer to right fielder J.D. Martinez that hit the top of the fence in right center after clanking off the hands of some paying customers.

That drew Detroit to 4-3, but Pittsburgh came back with four runs in the ninth.

Liriano (5-6) was 1-9 against Detroit in his previous 14 appearances.

An RBI double to deep center by Pirates designated hitter Andrew McCutchen in the ninth against Tigers right-hander Bruce Rondon bumped the margin up to 5-3. Walker smacked a two-run double to left center that make it 7-3 before a bases-loaded groundout by first baseman Sean Rodriguez brought in the final run.

Left-hander Kyle Ryan (1-2) went through the first three innings smoothly but in the fourth gave up a solo home run to left by catcher Francisco Cervelli. In the fifth, he walked the first two batters he faced. The Pirates executed a sacrifice bunt against reliever Al Alburquerque and then got a sacrifice fly from McCutchen for a 2-0 lead.

Ryan walked five, struck out four and gave up three hits.

In the sixth, third baseman Jung Ho Kang singled and went to third on a single by Cervelli to knock out Alburquerque. Walker, who had 10 hits in the series, bounced an RBI single to right against left-hander Blaine Hardy to put Pittsburgh up 3-0.

Left fielder Starling Marte put the Pirates ahead 4-0 with an RBI single in the seventh off Hardy.

All Detroit got through the first seven innings was manager Brad Ausmus thrown out of the game, for chirping about a called third strike to Martinez leading off the fifth.

NOTES: Pirates left-handed hitting LF Gregory Polanco got a rare start against a southpaw Thursday, striking out three times and walking twice. ... Tigers C Alex Avila served as Toledo's DH Thursday and while manager Brad Ausmus skirted the question, Detroit is likely to recall Avila on Friday. ... Pittsburgh now has an eight-game winning streak against American League teams. ... Pirates manager Clint Hurdle praised rookie Detroit C James McCann as "one of the best young catchers I've seen this year, from my perspective, because of the way he blocks the ball, the way he swings the bat and the way he catches."