It seems that Marcus Smart’s eye injury may be worse than originally thought.

The infection in the Celtics guard’s left eye that has kept him out of the team’s last three games has now spread to his right eye, Coach Brad Stevens said after practice on Monday.

Smart wasn’t at the Celtics’ practice facility as the team returned Monday and it’s uncertain when he will be back. Either way, his status seems to be in jeopardy as the Celtics return to action on Wednesday night at Dallas.

“You’re worried about it but I was told this particular type of infection could be 7-10 days,” Stevens said. “We’re at seven now.”

Stevens said Smart has met with multiple eye specialists but hasn’t received an update on the severity of the injury.

“He’s struggling a little bit,” Stevens said.

Without Smart, the Celtics’ best defender, the team has struggled on that end of the floor, giving up 122 and 115 points in their two losses to the Pacers and 76ers last week.

As the team practiced Monday, Daniel Theis said a big focus was on defense, where they’re trying to get back to their principles – the forward said their ball pressure has been lacking, and that Smart’s absence has contributed to their defensive drop-off.

Stevens wasn’t ready to go that far.

“We played really well in a few of the games without him,” Stevens said of Smart. “I think we’ve got a lot of good defenders. But clearly we’re going to be better with him. Obviously, selfishly, I’d like to have everybody back so that we can start to throw together our rotations and play guys together and try different things with regard to getting groups out there. But man, I just hope he gets better. It’s been a miserable week for him.”

Jayson Tatum echoed his coach’s sentiment. Without Smart, the Celtics are going to have to collectively step up to make up for his absence defensively.

“We can’t make excuses,” Tatum said. “Obviously, he’s one of the best defenders in the league but we can’t make any excuses when guys are out.”

ROBERT WILLIAMS, who has also missed the last three games with a left hip injury, is going to be out much longer.

The center was diagnosed with a bone edema in his left hip, and he’ll be re-evaluated in three weeks. Williams was at practice Monday using a stationary bike.

“Obviously tough,” Stevens said. “Need to make sure that the next scan looks better when he gets scanned again in three weeks.

“I don’t know what beyond that they’ve cleared him to do or what he will be asked to do. But obviously we want to progress slowly with that and the reason why we didn’t have a better answer for you last week is that we just wanted to have as many people see it as possible.”