Michael Waltrip Racing on Thursday picked Elliott Sadler to close out the season in the No. 55 Toyota while Brian Vickers is sidelined treating a blood clot.
Vickers informed the team Monday doctors had found a small clot in his right leg, and the blood thinners needed to treat it prevent him from racing. He's expected to take blood thinners at least two weeks.
Vickers also missed the final 25 races of the 2010 season with blood clots, and during that time required heart surgery.
Team co-owner Waltrip was already scheduled to drive the car this weekend at Talladega. Sadler will drive the car at Martinsville, Texas, Phoenix and Homestead.
Sadler has 431 Sprint Cup starts, and his three career Cup wins include a 2004 race at Texas. Sadler, like Vickers, drives a Joe Gibbs Racing Toyota full time in the Nationwide Series.
''First, I am already a teammate of Brian's at Joe Gibbs Racing and it is really tough to see him going through this again,'' said Sadler. ''Both of us have fought hard to get back in a position to win at NASCAR's highest level. I am honored to have this opportunity to drive for MWR because I know their cars are competitive.''
MWR had explored using Juan Pablo Montoya, who is moving to IndyCar at the end of the season, but Montoya wasn't interested. And talk of letting Kyle Larson use the four races as an opportunity to get seat time before he replaces Montoya at Chip Ganassi Racing never gained traction.
Waltrip said Sadler was the right driver all along.
''Elliott has all the attributes we were looking for. He's experienced, familiar with Toyota, has a great attitude, plus he's a heck of a driver,'' Waltrip said. ''We'll pair him with (crew chief) Scott Miller and the No. 55 guys and I know they'll have the Aaron's Dream Machine at the front of the field. I also want to thank everyone at Joe Gibbs Racing and Toyota for letting us borrow Elliott for a few races.''