CLEARWATER, Fla. -- There has been a legitimate change in Jon Lester's changeup this spring. With the left-hander down to one more exhibition start, he can now say for sure that the pitch he has been experimenting with for all of camp will not be left on the cutting-room floor when he makes his first regular-season start April 8 against the Rays.

Lester used the pitch, in his estimate, 10 to 15 times on Sunday against the Phillies. This on a day he gave up six hits and one run while walking four and striking out five against one of the best lineups in baseball.

Last year, Lester said he would throw the pitch "zero to one time" per start. He quipped that it was his ninth best pitch.

"This is the best game I've thrown with it," Lester said. "It felt really good. I was consistent with it. When I missed, it was in the right areas. I was pretty happy with it."

For a man who already has a strong fastball-cutter-curve combo, how will the changeup help him?

"I think it's going to be a pitch like we used today," Lester said. "When guys are cheating in, drop a changeup on them and they're out in front, and swing and miss or maybe hit a loopy foul ball. It makes them honor that fastball in and it makes them not cheat so much to get there, so I can get back to my strengths -- fastball-cutter in. It adds another pitch that they have to think about in the back of their head when they get up to the plate."

Though Lester won 16 games last year in breakout fashion, it is important to remember he is still just 25 years old.

"That's the key," said Red Sox catcher Jason Varitek. "Everybody needs to take a step back on him. I love him, but he is still developing. I know that, the staff knows that. He's going to have bumps, he's going to have some good times and some not so good times. He'll continue to grow."

And from what Varitek has seen, the changeup can be an important part of that development.

"Well, it gives him more completeness," Varitek said. "It widens his strike zone, widens the depth of the bat. It gives him one more weapon. He's starting to get a much better feel for it. He's used it more this spring than his entire spring."

Lester will next pitch at Citi Field in an exhibition start against the Mets on Friday night. Then it is on to the real games.

"I felt good," said Lester, who threw 88 pitches. "[My] last start felt good, [too]. I'm getting [my] legs under me. I'm starting to feel like it's go time and getting ready for the season."

Once that season starts, hitters should soon notice the "change" in Lester's repertoire.