Brad Keselowski remains cautious about his prospects of winning his first Sprint Cup title at this weekend's championship finale at Homestead-Miami Speedway, despite a healthy 20-point lead over Jimmie Johnson in the championship.

The Penske Racing driver finished sixth in last Sunday's race at Phoenix, where his main title rival endured a tough afternoon after hitting the wall due to deflating right-front tire that sent him to the garage for lengthy repairs, resulting in a 32nd-place finish.

Keselowski led the race twice for a total 10 laps but strategy calls meant he had to fight to get back his track position a number of times, including recovering from stalling his car in an early two-tire stop. He was glad to have regained the lead in the standings that he held for the first time when the playoff series started, but believes the title battle is still far from settled.

"Well, certainly if you have the choice you always want to be in the lead of the points, especially in the closing races, so I'm thankful for that," said Keselowski. "But I also know that the troubles that they had are the same troubles that we could have next week, and so you try not to take anything for granted.

"You try to just focus on what lies ahead, and we've got to do the best job we can at Homestead. That's where my focus is."

Keselowski cautious despite lead

Keselowski, the 2010 NASCAR Nationwide Series champion, is in position to deliver Penske Racing's first Sprint Cup title if he can finish 15th or better, even if Johnson wins the race. It would also give Dodge a championship crown on its exit from NASCAR competition. Penske announced in March of this year that it would switch to Ford cars in 2013.