The Seattle Sounders announced on Friday that forward Clint Dempsey is undergoing medical evaluations for an irregular heartbeat. As a result, Dempsey will miss Sunday's match against the Portland Timbers.

The Sounders are making no other details publicly available at this time while the medical process unfolds and information is gathered internally. A U.S. Soccer spokesman confirmed to MLSsoccer.com that Dempsey will not be called up for World Cup qualifiers against St. Vincent and the Grenadines and Trinidad & Tobago on Sept. 2, 6.

Currently in his fourth season with the Sounders, Dempsey has contributed eight goals and two assists in MLS action throughout 2016, including two goals last weekend against the Timbers. The 33-year-old has racked-up 72 regular-season appearances for Seattle, recording 37 goals and 23 assists across MLS regular season and postseason play since joining the club.

The situation also puts Dempsey's status in jeopardy for the US national team's upcoming World Cup qualifiers against St. Vincent & the Grenadines and Trinidad & Tobago.

At the national team level, Dempsey has scored 52 goals in 131 appearances, good for second all-time on the USMNT scoring charts. He has represented and scored for the the US in three World Cups and has also appeared in four CONCACAF Gold Cups, the 2009 Confederations Cup and 2016 Copa América Centenario.