Midfielders Patrice Bernier and Justin Mapp and forward Daniele Paponi also weren't on the field Thursday due to minor injuries.
Some of them, maybe even all of them, will be ready when the Impact play host to the New England Revolution on Saturday afternoon, but how much they can play might only be determined on the day of the game.
"Right now I can't say," said coach Marco Schallibaum. "But we have a couple of days.
"The good news is that Alessandro (Nesta) can play. As for Marco, Patrice and Justin, we'll know after practice (on Friday), but I'm confident to have at least two out of three of them. But even if we don't have this player or that player I think we have enough talent to win the match."
The club will also be without its two workhorse fullbacks. Jeb Brovsky, who has played all 30 games this season, is expected to miss the next three with a broken toe, while Hassoun Camara will serve a one-game suspension for accumulating five yellow cards.
Schallibaum hopes Brovsky can return for the final regular-season game Oct. 26 in Toronto and be ready for the playoffs.
On the plus side, Nesta is due to return after missing two games with a groin problem, and midfielder Hernan Bernardello is also back after missing more than a month with a sprained ankle.
Di Vaio, who leads MLS with 19 goals, had to leave a 1-0 loss in Houston on Friday night, but hopes to be ready to face the Revolution.
"It started in the warmup," the 37-year-old said. "I played because I wanted to help the team, but it was difficult and I wasn't able to continue.
"But I did the physiotherapy and now I feel a lot better and I'm confident I can play Saturday."
Bernier sat out for the first time this season in Houston with a hip problem, but he is also looking to play.
"I feel good," he said. "I'm training to be ready.
"I didn't play last Friday so that I would be able to play this game. Whether I come off the bench or I'm (starting), I don't know. It's not my decision. But my main goal is to at least be ready mentally and physically."
Bernier took the field near the end of the practice to kick the ball with for a few minutes with his teammates, but Mapp only ran laps.
The injuries have the club limping into a match that could have big playoff implications.
The Impact (13-10-7) are fourth in the Eastern conference with 46 points, seven points behind New York, six behind Kansas City and two behind Houston, but with two games in hand on all three rivals.
But they are only one point ahead of Philadelphia and three ahead of sixth-place Chicago.
The three points for a win wouldn't clinch anything, but it would put them ahead of Houston and keep their pursuers at bay. They travel to Los Angeles on Wednesday, then return home to face Philadelphia on Oct. 19.
In MLS, the top three teams in each conference go directly to the conference semifinals, while the fourth and fifth-place teams face each other for the right to face the first-place team.
With Brovsky out, Maxim Tissot is expected to start at left back. Captain Davy Arnaud, normally a midfielder, will likely fill in for Camara on the right side. Arnaud played some right back last season.
Central defender Nelson Rivas, who has yet to play this season due to a knee injury, has finally resumed practising with the team, but is not expected to suit up.
Arnaud was in the spotlight this week after the Nederland, Texas, native gave his first television interview in French. He did well, too.
The 33-year-old has been studying the language since joining the Impact last season. Arnaud's ancestors spoke the Cajun French of Louisiana, but he said his great-grandmother was the last in the family to speak it.