By Peter Abraham, Globe Staff

JUPITER, Fla. — The Red Sox are not going to make any decisions about their rotation based on one day in spring training. That Felix Doubront pitched well against the Florida Marlins on Saturday while Alfredo Aceves was getting rocked by the Philadelphia Phillies back in Fort Myers doesn’t necessarily put one ahead of the other.

“You have to look at the body of work,” manager Bobby Valentine said before the game. “I don’t know if today is a test. This stuff is so unfair.”

But for Doubront, the game was another entry on a resume that is impossible to ignore. He allowed one run over six innings to lift the Sox to a 4-1 victory before a sellout crowd at Roger Dean Stadium.

Doubront gave up five hits, walked one and struck out two while throwing 53 of his 78 pitches for strikes.

“He filled up the strike zone with all four pitches. He went right at guys. I haven’t seen him throw that well in a long time,” catcher Ryan Lavarnway said.

As Doubront cruised, Aceves lasted three innings against the Phillies, allowing nine runs on 10 hits, three of them home runs.

The other leading candidate for the rotation, Daniel Bard, will start against the Blue Jays in Dunedin on Sunday.

Doubront has a 2.70 earned run average in four spring starts and has improved steadily, giving up four earned runs in his last 14.2 innings. At 24, the lefthander appears on the verge of fulfilling the potential the organization has long believed he has.

“It’s a combination of good health and a sense of urgency,” pitching coach Bob McClure said. “He has to earn it and that’s the way we’re looking at it. We’re just not giving it away.”

Doubront threw only 87.2 innings last season. He reported to spring training in poor condition, strained his elbow early on and started the season on the disabled list.

Hamstring and groin injuries limited him to 18 appearances for Triple-A Pawtucket. Only three times all season did Doubront pitch six or more innings, the last time on July 6.

That made Saturday’s outing a notable one, even if it was in spring training against a Marlins lineup with only three of their expected starters.

“Today was good for me. I performed well with Bobby and Mac here. That’s what I got and the next time is going to be the same,” Doubront said. “I’m going to keep working and work hard for it.”

Doubront has spent part of two seasons in the majors but hasn’t stuck. Now, out of minor league options, this spring could represent his last chance to impress a team that signed him back in 2004 at the age of 16.

“I knew I had to show them what I could do,” Doubront said. “It was on my mind all winter. I worked hard, the hardest of my life.”

Lavarnway, who caught Doubront at Triple-A Pawtucket last season, saw the difference from the start of camp.

“I think a lot of stuff went wrong last year. It was really unfortunate it. He took that and learned from it. He took a bad situation and made that into a positive the way he came out this year, not only physically but emotionally. He’s a better ballplayer,” Lavarnway said.

“There was a certain look in his eye. He wants to not only pitch in the big leagues and not only pitch in the big leagues and not only be successful but be in the Boston Red Sox starting rotation.”

See the Globe tomorrow for more on Doubront.