Diekman, who was recalled from Triple-A Lehigh Valley on Friday, retired all four batters he faced and earned his first win in the big leagues in Tuesday's 4-3 win over the Astros.
"I don't think I could ever have dreamed about getting the win in my debut," Diekman said. "That's pretty crazy."
With Jonathan Papelbon unavailable, Chad Qualls was brought in for the ninth inning with the Phillies holding a 3-1 lead. Four hits and an error later, the game was tied. Antonio Bastardo was also unavailable, and so Diekman, the rookie, entered with runners on second and third and two outs.
"Nope, not at all," Diekman said, when asked if he'd imagined making his debut in that type of scenario. "I really thought I was going to have like a four- or five-run lead or something like that."
Diekman said he couldn't feel his legs when he was running to the mound.
"When I got put in, I had to make sure I didn't trip down the stairs first," Diekman said. "And then, I just wanted to make it all the way to the mound without tripping. That's the one thing that went through my head."
Any nerves he might have had didn't show, however, as Diekman more resembled a veteran than a rookie. The 6-foot-4 lefty, using a mix of a fastball that touched 93-95 mph and a slider, struck out Astros shortstop Marwin Gonzalez to end the ninth and send the game to extra innings.
Diekman came back out for the 10th inning and retired the side in order, striking out two more hitters.
"Diekman came in and did a heck of a job," manager Charlie Manuel said.
"He's got unbelievable stuff, so I expect a lot more of that," Cliff Lee said.
Diekman, 25, was promoted to aid a struggling bullpen. In 13 appearances with Lehigh Valley, he went 1-0 with a 0.59 ERA and five saves. After his callup on Friday, Diekman phoned his father, who cried upon hearing the news.
Diekman had not yet spoken to his father before talking to reporters after his big win. What would he say when he did?
"I got a ball for you," Diekman said with a smile.