David Backes scores his team’s third goal of the first period against Ondrej Pavelec of the Czech Republic. (Martin Rose/Getty Images)

David Backes scored with 1.8 seconds left in the first period to extend the United States’s quarterfinal lead over the Czech Republic. Meantime, Lauris Darzins came off the bench after a faceoff and scored on a breakaway to help Latvia tie the score with Canada, 1-1. That game, being playing concurrently with the U.S. game, is also at first intermission.

The winners of both games will advance to a semifinal to be played Friday. Finland and Sweden will meet in the other semifinal.

James van Riemsdyk scored early for the U.S., but Ales Hemsky beat Jonathan Quick for an equalizer just 4 minutes 31 seconds into the game. Dustin Brown broke the deadlock at 14:38 of the first, with a goal off assists from Ryan Suter and Backes. Then with the first period running out, Backes got a pass from behind the net and snuck a shot past Ondrej Pavelec.

United States vs. Czech Republic live summary | Canada vs. Latvia summary

More Olympic hockey news:

Analysis: Why Russia went out with a whimper

Russia falls to Finland, won’t win hockey medal

World reacts to Russia’s hockey loss

Hockey ouster heightens pressure on Russia’s ‘tiny genius’

D.C. Sports Bog: Milbury and Roenick rip Ovechkin

Quarterfinals schedule | Playoff bracket set

Analysis: Katie Carrera’s five thoughts from Feb. 16