The Brooklyn Nets lost more than just Game 4 of their second-round playoff series against the Milwaukee Bucks on Sunday. They also lost another star player as Kyrie Irving left the contest with a sprained right ankle, leaving his status for the most important games of the season in question.

X-rays on Irving’s ankle were negative and he will be further evaluated Monday. The point guard left Fiserv Forum using crutches and in a walking boot, according to ESPN’s Rachel Nichols, a discouraging sign for his Game 5 availability.

With the series tied at 2-2, the Nets host the Bucks Tuesday night.

“I have no idea what is going to happen with [Irving] in the coming days,” Nets coach Steve Nash said following Sunday’s 107-96 loss. “We will cross our fingers and hope that it is better than I don’t know -- better than what -- better than missing the next game?

“We all have to pitch in. We all got to play together.”

Brooklyn had already been without one of its superstars for essentially the entire series. James Harden hasn’t played since he exited Game 1 with right hamstring tightness less than a minute into the contest.

The Nets haven’t given a timeline for Harden’s return, but the same injury forced him to sit 21 games in the regular season. Nash made it clear that Irving’s status won’t affect whether or not Harden comes back.

“I don't want James to be rushed back,” Nash said. “If he’s able to play next game, or the game after, that's fantastic. If he’s not, we don’t want to rush him back and jeopardize doing something worse or making this a long-term injury.”

Since the Nets traded for Harden in January, the team has struggled to keep all of its stars healthy. Brooklyn usually had two of its big three -- Harden, Irving or Kevin Durant -- together on the court, allowing the team to earn the Eastern Conference’s No. 2 seed. The three stars played every game in the first round as Brooklyn easily took care of the Boston Celtics in five games.

Without Harden, the Nets still managed to average 120 points in Game 1 and Game 2 victories over Milwaukee. The Bucks barely escaped with an 86-83 Game 3 win.

When Irving went down in Game 4, Brooklyn became a different team. Durant was forced to take on the bulk of the offensive load, resulting in a 9-for-25 shooting performance. Durant averaged 31.8 points on 53% shooting in his previous eight playoff games.

Irving scored at least 22 points in each of the first three games against the Bucks. The Nets shot 4-of-19 from three-point range Sunday after Irving headed to the locker room.

The extent of Irving’s injury is not yet known. A Grade 1 ankle sprain might only keep an NBA player off the court for a few days. A Grade 2 sprain could result in a recovery period of a few weeks, though Hawks star Trae Young only missed nine days in the regular season with such an injury.

A potential Game 7 between the Nets and Bucks would be played Saturday. Milwaukee can end the series in three days with two more wins in a row.

Brooklyn Nets Kyrie Irving was fined $35,000 for violating the National Basketball Association's media access rules
Brooklyn Nets Kyrie Irving GETTY IMAGES NORTH AMERICA / Sarah Stier