Rich Harden pitched six strong innings in his season debut as the Athletics beat the Diamondbacks 5-4 on Friday night. Harden, who was reinstated from the 60-day disabled list earlier in the day, allowed two runs and four hits in his first start for Oakland in three years. "I was excited to get back out there," Harden said. "It's something to build on. I knew I had a limit but I never thought about it."