Defending champions the Chicago Blackhawks were knocked out of the NHL Stanley Cup play-offs after going down 3-2 in a thriller against the St Louis Blues on Monday.

Title holders the Blackhawks trailed 2-0 in the first period before battling back to tie the seventh and deciding game at 2-2 in the second.

Jori Lehtera scored the opener for the Blues one minute into the game and Colton Parayko doubled their advantage 12 minutes later.

Marian Hossa pulled one back for the Blackhawks before Andrew Shaw tied the game 3:20 into the second period.

The go-ahead goal came from Troy Brouwer approaching the midway mark of the third period.

Chicago came close to sending the game into overtime but Brent Seabrook's shot somehow hit both posts and stayed out.

The Dallas Stars await the Blues in the Western Conference second round.

Meanwhile, the Nashville Predators forced a deciding seventh game in their first-round play-off series against the Anaheim Ducks thanks to a 3-1 win.

The Predators went into the sixth game at the Bridgestone Arena down 3-2 in the series.

But after a scoreless first period, the Predators scored twice in the second through Mattias Ekholm and James Neal, before Ryan Kesler struck for the Ducks on the power play.

With the Ducks seeking to tie the game in the closing stages, Shea Weber scored into an empty-net goal to seal the win and avoid elimination.

The winner of the seventh game will face the San Jose Sharks in the next round.