Boston Celtics small forward Gordon Hayward is dealing with a left foot injury, an ailment Celtics president Danny Ainge admits “nobody knows exactly what the issue is.”

The Celtics are listing Hayward as day to day. The swingman is expected to undergo an MRI on Thursday. The left foot is the same foot Hayward suffered that gruesome ankle injury against the Cleveland Cavaliers on opening night back in 2017.

“He was doing a lot of training and being able to work and he just has a toe/foot — it’s right there, right where your toe connects with your foot,” Ainge said on 98.5 The Sports Hub with Toucher and Rich, via the Boston Sports Journal.

“It’s just some pain and we’re trying to figure out what it is. He had a cortisone shot, hoping that would make it better, but it actually made it worse. So we’re trying to figure all that out. Nobody knows exactly what the issue is.”

Hayward has played in just 11 games this season. He missed time due to a broken hand. The 29-year-old is averaging 17.5 points, 6.1 rebounds and 4.1 assists for the Celtics while shooting 55.6 percent from the field, 39.5 percent from beyond the arc and 78.3 percent from the free-throw line.

The Celtics, after defeating the Dallas Mavericks on Wednesday, are now 18-7 on the season. They are in second place in the Eastern Conference standings.

Hayward is making $32,700,690 this season. He has a player option worth $34,187,085 for next season. The veteran will likely pick that option up and remain with the Celtics since he has a injury history now.