"When I do have to face him, I now know how to pitch him, I think," Hamels said after facing the AL MVP three times in an exhibition on Saturday. "Don't throw anything near the plate."
Mauer had two hits and two RBIs and the Twins roughed up Hamels in an 8-4 victory over the Philadelphia Phillies.
Mauer, who signed an eight-year contract extension earlier this month that will kick in after this season at $23 million per year, is hitting .448 this spring. He had a single in the fourth inning and a two-run double in the fifth.
"Wow. Joe Mauer," Hamels said of the three-time batting champion. "He hit the ball hard."
Michael Cuddyer added a two-run double in the fourth and Jim Thome hit a two-run homer to the opposite field off Jose Contreras for the Twins. Cuddyer started the day leading the majors in batting average (.513) and on-base percentage (.568) this spring.
"It's a very, very talented lineup really from top to bottom," Thome said.
Hamels gave up five runs on seven hits and in 6 1/3 innings.
He was rolling right through the spring with a 1.69 ERA in three starts until the Yankees scored seven runs -- six earned -- on nine hits in four innings on Monday. Hamels said after that start that he wasn't concerned because he was working primarily on his fastball. He used all of his pitches on Saturday, including a curveball that he has added this offseason.
Despite giving up 11 earned runs in his past two starts and seeing his ERA rise to 5.57, Hamels said he feels great and is ready for the regular season to start. He'll come right after ace Roy Halladay in the rotation for the Phillies, who are looking for their third straight NL pennant.
"I'm healthy," said Hamels, who won the NLCS and World Series MVP awards in 2008 but struggled last season. "That's the biggest thing. That's something I've worked on so hard. I feel strong. And being able to go out there and having the confidence the way my body is going to respond, that's everything. That's the way you want to be in spring."
Greg Dobbs had a homer and a double for the Phillies.
Twins starter Nick Blackburn gave up two runs on six hits in four innings against a bunch of Phillies backups.
"I'm really glad I'm not facing our lineup," Blackburn said. "There are no breaks at all."
The Twins optioned INF Matt Tolbert to Triple-A Rochester and reassigned LHP Mike Maroth, C Danny Lehmann and outfielder Ben Revere to minor league camp. Manager Ron Gardenhire also informed OF Jacque Jones that he would not make the team, but he will stay with the team for now. ... Phillies CF Dewayne Wise just missed a home run in the first at-bat of the game. ... Attendance was announced at 8,162, the Twins' 11th sellout of the spring.