The former Bologna star striker was back in his home country on Thursday for the second time in two months to attend hearings into a match-fixing scandal that has rocked Italian soccer to its roots.
He will miss Montreal's home game Saturday night against Philadelphia and is expected to return on Sunday. Rookie Andrew Wenger is to play in his spot.
Di Vaio may be suspended up to six months if found guilty by a disciplinary committee of the Italian soccer federation (FIGC) for failing to report fraud in connection with a 2011 match in which Bologna lost 4-0 at home to Bari. Any suspension would likely include play in MLS. Bologna captain Daniele Portanova faces a three-year ban.
The 36-year-old Di Vaio, Montreal's lone designated player making US$1.9 million this season, said last week he wasn't worried because he had not done any wrong. His compatriot and Impact teammate Matteo Ferrari had his fingers crossed.
''I talked with him and he said he didn't do anything, so he's very fine,'' said Ferrari. ''But sometimes in Italy we are so strange, so I don't know what's going to happen.
''I hope just nothing because we need Marco.''
Dozens of players from more than 20 clubs, mostly in lower divisions, have been either arrested or questioned for match fixing or failure to report wrongdoings in the second scandal to hit Italian soccer since powerhouse Juventus was punished with relegation to Serie B, Italy's second division, in 2006.
Impact coach Jesse Marsch said he wasn't worried for DiVaio.
''I haven't even thought twice about it,'' he said. ''From everything I've heard, it's more like a deposition and less of a trial. I'm not too worried about it.''
The timing wasn't good. Di Vaio struggled to find his rhythm in MLS and it took eight games to score his first goal in last Saturday's 3-1 victory over the visiting New York Red Bulls.
The hope was once he got the first one in, the goals would come more regularly from the crafty striker.
''I wouldn't describe it as frustrating, just unfortunate because in training and in games now he's really looked sharp,'' said Marsch. ''I think he'll come back and be ready to go again, but it is unfortunate for him and the group, for sure.''
Wenger, the first pick in the MLS SuperDraft in November, returned last week from a hamstring injury and was a late substitute against New York. The 21-year-old has three goals in 13 games.
''Every time Andrew played, he played well,'' said Ferrari. ''He's fast, he's strong and good with both feet. He has a good chance now because Marco's not here.''
Getting all of the team's Italian connection on the pitch at once has proven difficult.
Other than forward Bernardo Corradi, who is lost for the season with a knee injury, the New York game was the first with Di Vaio, Ferrari, former Inter Milan defender Nelson Rivas and former AC Milan great Alessandro Nesta all available. Newly signed Nesta was outstanding in his first match, while Ferrari and Rivas returned from injury.
Now Marsch is looking at using a three-man back line with Nesta in the centre, Ferrari on the left and Rivas on the right. Hassoun Camara would play in an advanced right back position.
Ferrari said he only played on the left side a few times in his career, although once was against Dutch star Arjen Robben. This time he won't be in a traditional left back role.
''We tried to tilt it a bit so that Matteo's not an outright left back,'' said Marsch. ''It's a modified centre back position.''
Against New York, Nesta and Rivas started at centre back, and Ferrari reportedly was not pleased that it took until the 78th minute for him to enter the game to replace Rivas. Playing all three at once should keep the peace, although it bumps American Jeb Brovsky from the lineup.
''I have to do both, defend and attack, so it's a good thing,'' Camara said of the new set-up. ''We can find some space we wouldn't have at 4-4-2.
''With the great players we have behind in Nesta, Rivas and Matteo, I think we can be very good.''
They will need to be. The 8-13-3 Impact have only 10 regular season games left and need to pull off a winning streak to hold on to any hopes of making the playoffs.
An updated salary report released Thursday by the players association showed Nesta is earning $225,000, a modest figure for the four-time Italian defender of the year. The 36-year-old said when he signed it was not for the money but to play with his old friend Di Vaio.
The rest of Montreal's lineup against Philadelphia should be unchanged from the game against New York, with Patrice Bernier and Collen Warner just ahead of the back line, and with midfielder Justin Mapp on the left side, Felipe Martins in the middle and Davy Arnaud on the right.
The Impact will try to avenge a 2-1 defeat in Philadelphia on July 14 in which they tied the game in the 89th minute only to see the Union score two minutes into stoppage time.