The Boston Celtics could once again be missing Kemba Walker and Robert Williams with their season on the line Tuesday night in Brooklyn.

The Celtics announced Monday both players were doubtful for Game 5 of Boston's first-round series, per ESPN's Malika Andrews and others.

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Walker is nursing a knee injury, while Williams is dealing with an ankle issue.

The Celtics were always going to be considered underdogs against the Nets, but they will have an even more difficult task defeating Brooklyn without two key contributors.

Walker's knee has flared up at numerous points throughout the year, and it has made for a good deal of frustration in a disappointing season. Still, he profiled as a very necessary scoring presence in this series, especially with Jaylen Brown out and Jayson Tatum unlikely to sustain the Herculean performance he had in a Game 3 victory.

Williams, meanwhile, has been sorely missed in the frontcourt. The “Time Lord” frequently gave the Celtics a significant boost with his rebounding and rim-running, not to mention his tremendous energy and rim protection. Williams averaged 1.8 blocks per game during the regular season despite playing just over 18 minutes per game.

The Celtics were totally overmatched in Sunday's loss to the Nets. A depleted Boston team featured a rotation including Jabari Parker, Grant Williams and Semi Ojeleye. No disrespect to those guys, but it's hard for that group to compete against the talent on Brooklyn's roster.

Unfair as it might be, the load will once again fall on Tatum's shoulders if he hopes to prolong the Celtics' season.