"Tonight was just going to be a pitcher's duel," Robertson said. "Benson threw a good ballgame, but we scratched out a couple runs and held on. To go out there in a game like this and perform like that is huge for our confidence."
The Tigers maintained their two-game lead over Minnesota in the AL Central, and now lead third-place Chicago by five games.
The Twins and White Sox would probably both have to pass the Tigers for Detroit to fall short of its first playoff berth in 19 years.
"I think we are paying attention to both of those teams," first baseman Sean Casey said. "Every game matters at this point -- every win and every loss."
The Tigers start a three-game series Monday night at Chicago.
"We've got five on them, but that's no big deal," Robertson said. "We still have them coming up, and there's still two weeks left. We have to focus."
Baltimore has lost 14 of 18.
Robertson (13-12) had his fourth impressive start in a row, allowing six hits and walking one. He has a 1.29 ERA since giving up 10 runs to the White Sox on Aug. 24, but has only gotten nine runs of support in his last six outings.
"He was tremendous again tonight," said Tigers manager Jim Leyland. "Benson was real good, too. We knew it was going to be a real good matchup and we were fortunate to win it."
Todd Jones pitched the ninth for his 36th save in 40 tries.
Benson (10-11) lost despite pitching his third complete game of the year. He gave up seven hits and three walks, striking out six.
"Give that other guy credit -- he pitched well too," Benson said. "There have been plenty of games where they haven't scored for me, but there have been plenty where they have. That just happens."
In Benson's last three starts, he is 0-1 despite a 2.35 ERA.
"He pitched a great game again, and we didn't score again," Baltimore manager Sam Perlozzo said. "He could easily have 16 wins this year -- he's had six games where he's pitched at least seven innings, given up no more than two runs and not gotten a win.
"That's a lot of hard luck."
Baltimore had a great scoring chance in the third after Corey Patterson's leadoff triple down the right-field line. But Robertson got Chris Gomez to pop out and retired David Newhan and Brian Roberts on routine grounders.
"We really needed to get something out of that inning," Perlozzo said. "When that happens, you just hope it doesn't come back to haunt you."
The Tigers extended their lead in the seventh when Carlos Guillen led off with a walk and took third on a double by Matt Stairs, claimed off waivers from Texas on Friday. Benson intentionally walked Casey to load the bases and after Inge popped out, Infante hit a sacrifice fly.
- Casey was thrown out stealing in the fifth inning, the first time that had happened to him in over four years. The slow-footed Casey had been successful in eight straight attempts since being caught by St. Louis' Mike Matheny on June 29, 2002, while playing for the Reds.
- Baltimore needs to win Sunday and Thursday to avoid losing their second straight season series to the Tigers. The Tigers only won a single season series from the Orioles between 1995 and 2004.
- Tigers reliever Joel Zumaya (wrist) said before the game that he was available after missing a week, but was not needed.