The left-hander will try to avoid the road problems that have plagued Seattle this season, and improve on the team's 2-6 record on its current road swing when the Mariners face the Rockies on Saturday in the second game of the three-game set.
"I really didn't have anything but a fastball," Vargas said after his last start. "It was kind of opposite from my last outing, where I really couldn't throw a changeup for a ball. And all of them tonight were balls. It was just one of those nights where I had to go out there and battle.
"My fastball was a fastball, but if I missed with it, they were doing damage, because they didn't have to worry about any other pitch. It was just a grind."
The Rockies will counter with a lefty of their own, rookie Christian Friedrich. The 24-year-old has dazzled in his first two career starts, allowing just one earned run in each appearance. Friedrich has struck out 17 and walked just two.
"This kid has worked really hard and gotten himself into a really good place," Rockies manager Jim Tracy said after Friedrich's debut. "He did exactly what I thought he was going to do from what I thought in Spring Training -- establish his fastball, pitch with his fastball and mix in his breaking stuff."
Mariners: Offense struggling with runners in scoring position
After going 1-for-6 with runners in scoring position in Friday's 4-0 win over the Rockies, the Mariners fall to just 3-for-24 on through eight games on their current road trip.
Kevin Millwood's shutout Friday was the first time a Mariners starter has gone the distance this season.
Rockies: Slump threatens stellar Interleague record
Since 2006, the Rockies own the best National League record in Interleague Play at 56-38. But, if they can't turn around their current slump, the Mets (50-47) could close in on that lead. With Friday's loss to the Mariners, the Rockies have now lost 11 of their past 13.
Friday's meeting between the Mariners and Rockies was the first meeting between the teams since 2009. The Mariners lead the all-time series 14-12.