The defending champions are currently in fourth place, one above the Scarlets, and Biggar says his side's season will be judged on what happens over the next three games.
The Ospreys face trips to Glasgow and Leinster in a tough run in so tomorrow night's game takes on extra importance.
"We're getting to the business end of the season now and it's important we keep our momentum going," said Biggar, who recently signed a new deal with the region.
"We've picked up two wins in our last two games which has allowed us to keep hold of fourth place and we know we are probably going to have to win all three remaining matches to progress.
"We have to concentrate on our own game, starting with Saturday night and Treviso."
With Welsh internationals Adam Jones, Richard Hibbard and Justin Tipuric all starting, the Ospreys will go into the meeting with the Italian side as overwhelming favourites. But Biggar and his teammates have previous experience of the danger the Italians can pose.
Treviso were 12-6 winners in the reverse league fixture at the start of the season, drew with Ulster at Ravenhill last month and recently got the better of the Cardiff Blues.
August's defeat out in Italy was part of a poor start to the season for the Ospreys but they have bounced back impressively to stay in contention for the title.
Biggar said: "We regrouped well after a poor start and we've gone on a pretty decent run. Now it's about making sure we finish the season off well with real momentum and some positive results. If we do that, anything is possible."
Looking at the Italian side, the Wales man added: "Treviso are a team that will always present a huge challenge.
"They are a side who can come here on Saturday with a sense of freedom, without any pressure on them and look to play an adventurous game of rugby. We are going to have to really be on our mettle to get anything out of the game.
"They keep on improving every year and have become a very good team as we've seen for ourselves when they've beaten us. We don't need reminding about the threat they pose.
"They got a great result in Ulster last month and we have to make sure we are at our best if we want to avoid a similar score line or worse on Saturday."
Biggar again teams up with Kahn Fotuali'i at half back tomorrow with Alun Wyn Jones leading the side.
Head coach Tandy said: "We've reached the time of the season now where there is no margin for error.
"The Scarlets are snapping at our heels so we will have to be at our absolute best for these three final games if we are going to secure a play-off place."