Adams was injured in the opening minutes of Monday's Premier League draw against Manchester United.
- Will another injury derail Adams' World Cup prep for the U.S.?
"Tyler has torn his MCL, so he will definitely be out for some time," Iraola said. "From our previous experience with MCL injuries, it is normally around two or three months.
"It's a big blow because he is an important player for us. Straight away, when you see the mechanism of the injury and the action itself we felt it could be something serious."
Adams' injury is also a potential blow for the U.S. team ahead of next year's World Cup. Adams has had lengthy injury layoffs in recent seasons and underwent back surgery last year. But he has been a near ever-present for Bournemouth this term.
Adams captained the United States at the 2022 World Cup in Qatar.
Mauricio Pochettino's side has four friendlies remaining before it begins its 2026 World Cup campaign against Paraguay at SoFi stadium in Inglewood, California, on June 12.
The U.S. is scheduled to play Belgium on March 28 at Atlanta's Mercedes-Benz Stadium, Portugal at the same venue three days later, followed by Senegal in Charlotte on May 31 and then Germany in Chicago on June 6.
Information from The Associated Press was used in this report.
