NFL Players Association president JC Tretter sharply criticized the conditions of the playing surface at Chicago's Soldier Field after the Bears defeated the Kansas City Chiefs 19-14 on Saturday.

The field had patches of missing grass and big divots, apparently due to a recent Elton John concert held at the facility.

The concert was held Aug. 5 and left damage the entire length of the field.

"The NFL said that this field met minimum testing standards," Tretter said on Twitter. "We clearly need to re-evaluate what is an acceptable surface for players to compete on. We need new testing metrics looking at the performance and safety of every field. The NFL can and should do better."

The Chicago Fire of Major League Soccer previously announced it will play its Aug. 21 against New York City FC at nearby SeatGeek Stadium in Bridgeview, Ill., "due to the expected field condition at Soldier Field from a series of planned events at the venue."

First-year Bears head coach Matt Eberflus defended the field conditions.

"I'm new here so I don't know the situations, but I know the guys are trying to do their best, and the playing surface was passed by the NFL for us to be on," Eberflus said. "I thought it was firm and it was good, so that's where we'll leave it at."

Chicago quarterback Justin Fields has seen the turf troubles before.

"I mean, it's kind of always been like that," Fields said. "It definitely was better than the family fest (on Tuesday). I'm just glad it was better than it was earlier this week because it wasn't the best. The grass could definitely be better for sure."

Soldier Field is the oldest stadium in the NFL and has been the Bears' full-time home since 1971. The facility opened in 1924.

However, the franchise reached agreement last September on a purchase agreement to build a new facility in Arlington Heights, located about 30 miles northwest of Soldier Field.

Tretter, a center, was released by the Cleveland Browns in the offseason. The 31-year-old has played in 111 games (90 starts) in eight NFL seasons with the Green Bay Packers (2014-16) and Browns (2017-21).