While the Bruins have the momentum after winning the last two games against the Blackhawks, the series has been tightly contested. Sure, the Black and Gold outplayed Chicago in all aspects in Game 3 Monday night, but they know that they’ll get the Hawks’ best shot in Game 4 as they try to tie the best of seven before the series shifts back to the United Center for Game 5 Saturday night.

But unlike Game 3, Marian Hossa is expected to suit up tonight after missing out last time due to an upper-body injury. That is huge news for the Blackhawks as they try to shake off their loss from Monday night.

With or without Hossa, the Bruins will either take a 3-1 series lead or the Blackhawks will tie the series at 2-2. That is a major difference in how teams would approach Game 5 Saturday night.

In any event, tonight’s game is crucial.

“This is a real big game,” defenseman Dennis Seidenberg said. “It’s either going to be 3-1 or 2-2, so it’s a big change of events tonight.”

After clinching their second game of the series, the Bruins went on to win their third game in the first attempt. That momentum is something they hope to sustain again as they try to accomplish that feat for the fourth straight series.

But a Blackhawks win would shift the momentum back to their side.

“It’s about making your breaks and taking advantage of them when you have them,” said head coach Claude Julien. “That’s why we’ll have some discussions on whether you can build momentum or not, whether coaches believe in it or not.

“As I said, you always have to focus on the game that you’re going to play that night, which is tonight. I’m not looking at, ‘we’ve got momentum now because we won the last two’. I don’t believe in that. They understand how important this game is, and so do we. It’s going to be a battle out there today.”

The Blackhawks are going into Game 4 as the more desperate team. But the Bruins, in their own right, will be desperate as well.

With so much at stake, the intensity level will ratchet up a notch at a boisterous TD Garden.

“It’s huge. I think both teams are desperate if you look at what’s at stake,” said forward Patrice Bergeron. “It’s huge and we know that every game is so important. So that’s why we have to increase our [intensity] level every game.”

At the end of the day, it’s about staying focused on the task in hand. And that task for the Bruins is taking a 3-1 series lead.

“We’re at a stage right now where I think we just got to stay focused,” said Julien. “My job is to keep our team focused on the present, not the future. That’s the most dangerous thing right now is to try to look ahead. We have a job to do tonight – not tomorrow – but tonight. I think our guys have to be ready for that challenge that we’re going to get tonight.”