The 25-year-old signed for Penske to drive for the squad full-time in both the Sprint Cup and Nationwide Series from 2010, but the team announced Monday that he will replace Stremme starting next weekend at Texas.
Keselowski tested for the team today at Daytona, sharing time on the track with his new team-mates Kurt Busch and Sam Hornish.
"Penske Racing wants to give Brad an opportunity to work with the team and get to know the race car as we prepare for the 2010 season," team owner Roger Penske said. "These three races will provide a good base for both Brad and the team as we head into next year.
"Penske Racing also thanks David Stremme for his contributions to the team this year. We wish David the very best moving forward."
Keselowski and Busch made contact and ignited the final wreck of Sunday's Cup race at Talladega, but on Monday they both seemed at ease while working both on and off the track at Daytona, when they tested tyres for Goodyear.
The Nationwide and Sprint Cup series race winner hopes the next three weeks can help him and his team get as best prepared as they can for the start of their first full season together.
"I am very excited to begin working with the Penske Racing team and I look forward to competing in the No. 12 Penske Dodge in the final three Cup series races of the year," Keselowski said.
"We all have high expectations for next season and beyond and being able to race with the team this year will only help us as we look toward 2010."
Stremme's future remains uncertain, but he is expected to compete in the Nationwide Series next year.
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