SAN ANTONIO — The Spurs will be without head coach Gregg Popovich for Game 4 of the first round Sunday afternoon against the Warriors.

San Antonio assistant coach Ettore Messina will fill in as head coach in Popovich’s absence.

After battling an undisclosed illness for an extended period, Gregg’s wife, Erin Popovich, died early Wednesday. She was 67. Erin and Gregg were married for four decades and had two children — Jill and Mickey — as well as two grandchildren.

Messina, 58, is in his fourth season as a Spurs assistant. With Popovich gone Thursday, Messina sat in the top seat as San Antonio dropped Game 3, 110-97.

In 17 seasons as a head coach in the EuroLeague, Messina went 279-98. He has been the head coach of the Italian national team since 2015.

Connor Letourneau is a San Francisco Chronicle staff writer. Email: cletourneau@sfchronicle.com . Twitter: @Con_Chron

  • San Antonio Spurs assistant coach Ettore Messina shouts to the team during the first half of Game 3 of a first-round NBA basketball playoff series against the Golden State Warriors in San Antonio, Thursday, April 19, 2018. (AP Photo/Eric Gay) Photo: Eric Gay, Associated Press
Photo: Eric Gay, Associated Press
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San Antonio Spurs assistant coach Ettore Messina shouts to the team during the first half of Game 3 of a first-round NBA basketball playoff series against the Golden State Warriors in San Antonio, Thursday, April 19, 2018. (AP Photo/Eric Gay) less
San Antonio Spurs assistant coach Ettore Messina shouts to the team during the first half of Game 3 of a first-round NBA basketball playoff series against the Golden State Warriors in San Antonio, Thursday, ... more
Photo: Eric Gay, Associated Press