The feud between the two seemed to go to another level when Kyle Busch set up his own Truck series team, Kyle Busch Motorsports in late 2009, and poached Rick Ren, Ron Hornaday's crew chief, from the Kevin Harvick Incorporated outfit, since which time KBM has gone from strength to strength,
In next week's race at Charlotte on May 20, KBM marks a landmark moment by fielding former F1 world champion Kimi Raikkonen in his debut in any NASCAR-sanctioned race.
But this week it's all about Dover - a place that Busch says he enjoys, but where he hasn't had the best of luck in the Truck series. "It's definitely a fast racetrack. It's a fun racetrack, too. It makes it interesting when you get to traffic," he said. "I should've won the past five races in a row at Dover, I just haven't been able to do it."
And now he faces the added obstacle of a fired up and motivated Harvick.
With both drivers under probation for four weeks - which includes their appearances in the Truck and Nationwide series as well as the Sprint Cup races and the All-Star event at Charlotte Motor Speedway on May 21 - both drivers will have to be careful not to commit any overt indiscretions that might attract NASCAR's ire.
But there is more than one way of wrecking someone else's race or making sure they don't get to victory road, and both drivers will be keeping their eyes open for any such opportunities on Friday night. Trouble there could spill over into Sunday afternoon's Sprint Cup race as well, making it an interesting weekend in store for NASCAR fans.