BALTIMORE (AP) -- Once Chris Tillman got through the first inning, it became apparent the right-hander was going to be tough on the Seattle Mariners.

And that is precisely what happened.

Tillman took a three-hit shutout into the eighth inning to extend a run of successful starts by Baltimore pitchers, and the Orioles beat Jason Vargas and the Mariners 3-1 on Monday night.

In his first five starts since being recalled from Triple-A Norfolk on July 4, Tillman gave up 13 first-inning runs. He broke the pattern in this one, putting the Mariners down in order on 12 pitches.

''It was big,'' Tillman said. ''I went out with the mindset of one inning at a time. (The first inning) has been kind of a downfall for me, but I knew what I needed to do to get through it and I made some pitches.''

Tillman (5-1) gave up one run, five hits and a walk in 7 1-3 innings to win his fourth straight start and lower his ERA to a sparkling 2.38. After jockeying between the minors and majors since 2009, Tillman seems poised to stick with Baltimore.

''It feels good,'' he said. ''I feel like I put a lot of work in in the offseason and carried it into the season and spring training and what not. I feel like it's starting to pay off here, and we're not done. We have a long way to go. We've got a lot of season left and we've got to keep working until we're done.''

Nick Markakis homered and Mark Reynolds had three hits and an RBI for the Orioles, who have won six of eight to improve to 58-51. Baltimore didn't record its 58th win last year until Sept. 9, one day after its 85th defeat.

This season, it's all about pitching. The Mariners scored in the eighth to end a streak of 28 scoreless innings by Baltimore pitchers; over the past four games, Orioles starters have given up two runs over 27 innings.

Tillman certainly did his part.

''His fastball had good life up in the zone,'' Seattle's Eric Thames said. ''He had a good changeup. All of his stuff was pretty much on today. Whenever we were sitting on counts, he threw the opposite pitch. It was just one of those days.''

Pedro Strop got two outs in the eighth and Jim Johnson worked the ninth for his 33rd save in 36 tries.

Vargas (12-8) allowed three runs - all in the second inning. Seeking to become the first Seattle pitcher in nine years to win six consecutive starts, Vargas yielded eight hits, struck out two and walked none in going the distance.

''It says a great deal about him and how far he's come,'' manager Eric Wedge said. ''He had earned the right to stay out there. I wanted him to be out there. I trust him.''

Munenori Kawasaki drove in the lone run for the last-place Mariners, who have lost three of four following a seven-game winning streak.

After stranding runners at second and third in the first inning, the Orioles went up 3-0 in the second. Lew Ford singled and scored on a double by Reynolds before Markakis drove a 1-2 pitch over the scoreboard in right field, the first homer allowed by Vargas in four starts since July 16.

Tillman held the Mariners hitless until the fifth, when Mike Carp hit a sharp grounder where shortstop J.J. Hardy would have been positioned had the Orioles not been in a shift to provide extra coverage to the right side of the infield.

In the Seattle sixth, Kawasaki reached on a bunt and advanced to third with one out but was stranded.

The Mariners finally broke through in the eighth. Thames hit a leadoff double and scored on a single by Kawasaki, who was tagged out at second on the play after the throw to the plate was cut off.

NOTES: The eighth-inning run prevented Baltimore from recording a third straight shutout. The Orioles haven't had more than two consecutive shutouts since notching five straight in September 1995. ... Seattle RHP Blake Beavan seeks to win a fifth straight start Wednesday night. Zach Britton will pitch for Baltimore. ... Orioles DH Jim Thome will be out until well into September with a herniated disk. The 41-year-old slugger was told last Thursday to rest for 30 days. ... The last Seattle pitcher to win six straight starts was Joel Pineiro in 2003.