Montreal (0-3-0) directed 25 shots toward the Seattle goal on Sunday, but couldn't find the net.
And then the Impact fell victim to defensive lapses as the Sounders spoiled its home opener at Olympic Stadium with a 2-0 victory on Sunday.
An own goal off a Lamar Neagle's header only eight minutes in and a goal from Obafemi Martins early in the second half was all Seattle (2-1-0) needed against a punchless Montreal attack.
"When you look at the game in terms of possession and our ability to get in good spots and get quality crosses in, to come away with nothing — it just seems we're not getting any little breaks," said the Impact's still-winless new coach Frank Klopas. "The guys worked hard and nothing's going for us right now. That's the frustrating part."
Di Vaio, a 20-goal scorer last season, and midfielder Andres Romero finished serving the three-game suspensions they incurred in a skirmish at the end of a playoff game in October. Both will be back for Montreal's game Saturday in Philadelphia.
Without their 38-year-old Italian striker, they have managed only two goals in three games. But the hard part for Klopas, whose mandate was to tighten the defence, was that they have conceded six.
Defender Matteo Ferrari said it would be unfair to expect Di Vaio to step in and solve all the team's problems right away as he hasn't played a real game in five months.
He hopes to see better all-around play from the team.
"We have to work hard on the defensive part — not just the four on the defence but the attitude of the team," said Ferrari. "We took six goals. It's too much.
"But I want to stay positive. It's the beginning of the season and the coach knows what to do, so forget about the standings right now and just keep working."
Still, it should help to have an experienced finisher. The Impact had a 25-9 edge in attempts on goal and 6-4 lead in shots on target. What was missing was someone to bury the chances as forward Andrew Wenger and midfielder Felipe Martins fired blanks for a second game in a row.
Down 2-0 in the second half, the Impact went on full attack. Substitute Blake Smith nearly had one in the 84th minute, but his shot was swept off the line by Djimi Traore.
"Two factors (Di Vaio) brings — fear to the other team because maybe they're more on their heels, and maybe more confidence to our team knowing that we have a guy that can change a game on the spur of the moment," said Impact midfielder Patrice Bernier, who played his first home game since he was named team captain.
"That's a benefit, but still, as a team, we have to be a unit. We create chances, but maybe give a little to much to the other team. Maybe his fresh legs that can give us a spark in Philly so we come out with some points."
The Sounders, coming off a 2-1 defeat last week to Toronto FC, could easily have been up by three goals in the first half.
Neagle, who spent the 2012 season with Montreal before being traded back to the Sounders, headed a Gonzalo Pineda free kick out of a crowd and saw it hit the crossbar and deflect off goalkeeper Troy Perkins and into the net in the eighth minute.
"It comes off the bottom of the crossbar, hits me in the arm and goes in," said Perkins. "You can sit there and say he'd have been better off just watching it, but I tried to make a play and was a little unlucky."
Seattle nearly had another in the 17th minute, but Perkins reached back to get a hand on Martin's header. And in the 32nd minute, Neagle's long low shot went off a goalpost.
The Sounders struck again in the 58th minute, when Neagle passed across the front of the goal and Kenny Copper chipped it back for Martins to head into an open side with the Impact defence standing still in front of Perkins.
"I knew we'd absorb some pressure," said Seattle coach Sigi Schmid. "We wanted to get forward on the counter and I figured we could create some chances off that.
"It's been a long road trip with the extra day, but I thought we did a good job. Perkins makes an unbelievable save on Obafemi's header and Lamar's unlucky when he hits the inside of the post and it goes across in the first half. But I thought we did what we needed to do."
The game was originally scheduled for Saturday but was postponed a day due to fears of an accumulation of snow on the domed stadium's roof, which is slated for replacement. Montreal is 4-2-3 in games played at the Big O.
"When we trained on Saturday we had a little more of a fun training session,"said Schmid. "The guys had a bit of fun with it. We just told them it was Groundhog Day and we'll repeat everything again."
Notes: It was Montreal's first loss to Seattle in three MLS meetings. . . The Sounders were without their big off-season signing Clint Dempsey due to a two-game suspension for hitting Toronto FC defender Mike Bloom in the groin last week. ... Montreal has two more games at Olympic Stadium, April 5 against New York and April 12 against Chicago before moving outdoors to Saputo Stadium.