The 36-year-old former Bologna star was called back to attend a hearing into allegations of match-fixing in Italian soccer and is due back on Friday to begin preparations for his Major League Soccer debut.
Di Vaio is not suspected of participating in match-fixing, but he said investigators want to question Bologna players about a few matches they played in 2011 against clubs that are under suspicion.
''There were a few games in particular they want to ask about,'' he said through an interpreter. ''The whole team has been called in.''
Di Vaio may have thought he was putting the turmoil in Serie-A behind him when he left Italy three weeks ago to join the Impact, an MLS expansion team with a strong Italian presence.
Montreal (3-7-3) made the quick forward its first designated player in a bid to add punch to an attack that has produced only 15 goals in 13 games. A designated player is one who is paid more than the league maximum but counts for less against the salary cap.
He isn't able to play until the summer transfer period officials opens, which puts the target date for his Impact debut at June 27 when Toronto FC visits Saputo Stadium.
Di Vaio took a short vacation with his family in Florida before he began working out with his new team, which includes former Serie-A players Matteo Ferrari, Bernardo Corradi and Nelson Rivas.
''I'm ready to get to work, and get to know my teammates,'' he said. ''Unfortunately I have to return to Italy to take care of some business, but I'm looking forward to getting back. I'm excited for the first game, but it's not too long to wait.''
He is to return to Montreal in time for the reopening on Saturday of Saputo Stadium, which has been expanded from 13,000 to 20,000 seats. Montreal will play host to the Seattle Sounders under the stars and on a grass pitch after playing its first five home games indoors at Olympic Stadium.
''We've got to make it our home, so from the first second we have to set the tempo and show people that it'll be tough to come in here and get a point,'' said midfielder Patrice Bernier. ''We're lucky to get two home openers in a year.''
Bernier was impressed by his new teammate Di Vaio, who reminds him of former Canadian national team striker Tomasz Radzinski, who had a productive career as a tricky, smaller striker with Everton and some European clubs.
''They have the same body structure and they move the same way,'' said Bernier. ''It's nice to have someone with something new to bring and maybe we can feed off that.
''We know he'll be a valuable addition. He's smaller, more mobile. He's got some speed. In this league, which is speed or strength, he'll bring something. And he's crafty. It'll be nice to see a guy who can score not just from the box but maybe from creating plays outside.''
Di Vaio is expected to partner with Corradi, a tall, lumbering forward who brings a physical presence. Coach Jesse Marsch has also tried to boost the attack by using five midfielders instead of the 4-4-2 formation from earlier in the season.
He said that allows him to use the talented Bernier, who sat out several games, along with Collen Warner and Felipe Martins in the centre of the field, to control the ball more from the midfield instead of playing a lot of long balls up to the strikers.
The Impact are coming off a three-week break since a 3-2 loss in Colorado and are entering the second of what Marsch calls three stages of the season. They opened the campaign playing eight of 13 games on the road, but will play six of 10 at home leading up to the July 25 all-star game, when the final stage begins.
By then, Di Vaio should be integrated with his new team.
''It's exciting to get him here and get him going,'' said Marsch. ''It was a good first day just to get him on the field and get assimilated to this.
''I think the adjustment will be smooth because of his familiarity with some players on our team, the discussions we've had about soccer and, above all, that he's an intelligent player. Guys like that fit in with any team.''
It won't be pleasant business in Italy for Di Vaio dealing with a problem that has put a negative spotlight on all of Italian soccer.
''But maybe it's a chance to start from zero and do things properly this time,'' he said. ''Find out the problems and try to fix them.''
When asked if the match-fixing may cause more Italian players to leave home, he said it was possible.
''Italian soccer doesn't have the same respect it once had with problems like this and players might be looking to go to Spain or France or other countries to play.''