PHOENIX -- If it was the last time he pitched at Chase Field, Randy Johnson certainly left D-backs fans with a lasting impression of his Hall-of-Fame career with an ageless performance in Sunday afternoon's season finale.

The Big Unit turned in his best start of the season, allowing just one unearned run on two hits as he went the distance in the D-backs' 2-1 win over the Rockies. The performance evoked memories of the days when the lefty was a perennial Cy Young Award candidate.

"The look in his eye, the intensity, I think a lot was similar to the years he was winning Cy Youngs and winning 20-plus games," said Arizona manager Bob Melvin. "He had a different feel for him today. You could tell the minute he took the mound. He was very intense today."

Melvin said Johnson approached him after the D-backs officially had been eliminated from postseason contention on Thursday and said: "You can throw the pitch count on Sunday out."

"I knew right then and there it was a little more than just another game for him," Melvin said.

The 45-year-old proved he still has some gas left in the tank, even if he's not lighting up the radar gun anymore. He finished the season 11-10 and with 295 career wins. He certainly could have had quite a few more wins after being the tough-luck loser or receiver of no-decisions countless times this year.

Johnson is set to become a free agent. So, will he be back with the D-backs in 2009?

Johnson said he thought about Sunday's game potentially being the last of his career in Arizona, but he hasn't decided whether he will play another season and strive for 300 wins to finish an illustrious career.

"I haven't even thought about that," Johnson said. "I don't even know what I'm having for dinner tonight, so I surely couldn't answer something like that. It's way too early to talk about that."

Melvin said it probably is unanimous that everyone with the D-backs would like to see Johnson back, adding he would be very surprised if the veteran lefty didn't want to return for another run.

"He's going to have to make that decision, too. I haven't talked to him about what his feelings are," Melvin said. "A competitor like him, who loves the competition, there are a lot of other things that factor in -- the travel, his family, all those type of things -- but he does have 300 on the horizon. I know he wants to accomplish that."

Colorado's Clint Barmes led off the game by reaching base on a throwing error from Mark Reynolds. Barmes scored three batters later on a wild pitch from Johnson. The Big Unit allowed only one hit to reach the outfield all game, and he was equally dominant in the first and ninth innings. He entered the ninth with 100 pitches and needed just five to retire the side in order.

It looked for a while as though Johnson again would be a tough-luck loser, as the D-backs trailed, 1-0, until the eighth inning. But Chris Young hit a game-tying home run.

Melvin said there was no way he would have considered taking Johnson out of the game with the way he was pitching.

"I wanted it to be his game today, based on how he was doing at the time, and it looked like he had a lot left in his tank," Melvin said. "It was going to take an extraordinary circumstance for him to come out of the game.

"His last few innings were as good as any of the innings that he had. Sometimes it takes a little while to get going, but not today."

In the bottom of the ninth, Miguel Montero reached base on a one-out walk. Melvin sent in pinch-runner Alex Romero for Montero. After Augie Ojeda singled and Jeff Salazar walked to load the bases, Young worked a game-winning walk.

"I guess you really couldn't ask for anything more the way the game ended today," Johnson said. "To go nine innings and to have everything kind of develop the way it did, it's a nice way for everybody to end the season."

It was Johnson's second complete game of the season. The previous one, however, came in a losing effort in Minnesota and was eight innings.

The Big Unit walked off the mound after getting Ryan Spilborghs to ground out with a roaring ovation. He followed with a rare curtain call.

"It was pretty heartwarming," Johnson said. "You've got to do a lot of things as a pitcher to get a curtain call. It meant a lot to me. It was great."

Johnson was very mum on his thoughts about his future, but his performance on Sunday just reassured him he doesn't have to hang it up quite yet, if he doesn't want to.

"I've always felt like I could still pitch at this level and still be successful. Maybe not as consistently as I once did, but when you're doing something that very few other people are doing, the bar is going to be set pretty high," Johnson said. "I'd rather have that bar set really high than no bar set at all. I still enjoy going out and pitching a game like I did today. That just reassures you that you could still be competitive at this level."