The Celtics lost a key player for the playoff push — we’ve seen this before in Boston

Subtracting the shot-blocking Robert Williams from the lineup deals a blow to the Celtics' championship aspirations.Matthew J Lee/Globe staff

Everything was looking perfect. Too perfect.

The Celtics beat the Timberwolves, 134-112, at the Garden Sunday, moving into the top spot in the Eastern Conference with their sixth straight win. They had leads of 20 or more points in all of those games, including four on the road, one against the mighty Warriors in San Francisco.

Dating back to early January, the Celtics were 29-7, clearly playing the best ball in the NBA. We were suddenly talking about them as championship-bound. Why Not Us? Banner No. 18 this spring seemed like more than a dream.

Then we found out that pogo-stick center Robert Williams suffered what was first termed a left knee sprain in the second half against the T-Wolves. A day later, we learned that it was a torn meniscus. On Wednesday, the 24-year-old dynamo had surgery that will shelve him for at least four weeks, probably longer. Whenever Williams returns, it’s hard to imagine he’ll have the same explosiveness. Not this year.

Poof. Just like that, the Celtics are no longer potential 2022 NBA champs. It’s still possible, of course, but the dream is dashed by the subtraction of the shot-blocking, lob-stuffing Time Lord. Without the explosive, rim-protecting presence of Williams, the surging Celtics probably don’t have enough to go all the way this year.

Like William & Mary and Guadalajara in “My Old School” … Daniel Theis and Grant Williams won’t do.

It’s a crusher of sorts. A sky-is-the-limit Celtics playoff spring suddenly feels like it’s going to be an uphill battle when they get to the second and third rounds against teams from Philadelphia, Milwaukee, and perhaps (gulp) Brooklyn. If the Celtics do advance to the later rounds, we’ll have the endless, soul-sucking updates about Williams’s recovery from surgery.

Daniel Theis and Grant Williams figure to get more time with Robert Williams sidelined.Mary Schwalm/Associated Press

Remember waiting for Kevin Garnett (injured right knee in February) in 2009? We waited and waited, but Garnett never made it back, missed the entire playoffs, and the defending world champion Celtics were bounced in the second round.

How about waiting for a crumbling, ready-to-retire Shaquille O’Neal in 2011? It was a drain on everybody. Waiting for Shaq’s foot. Waiting for Shaq’s Achilles’. Watching Shaq leave the Garden in a wheelchair. At one point, Doc Rivers updated us on Shaq’s solo practice in an empty gym and reported, “Shaq worked out against the cones and he was a dominant force.”

Shaq wound up giving the Celtics 12 playoff minutes, scoring 2 points.

The Boston sports landscape is littered with teams that could have gone all the way if not for an untimely injury to a star player. The 1946 Red Sox were prohibitive favorites to win the World Series against the Cardinals, but MVP Ted Williams got hit in the elbow by a pitch in a meaningless “tuneup” exhibition game and was rendered useless, hitting .200 (all singles) in the seven-game defeat.

In 1967, the Impossible Dream Sox made it to the Fall Classic without young home run hitter Tony Conigliaro, who was felled by a pitch to the head in late August and didn’t play for a year and a half. The Sox lost that series in seven games.

The 1975 Red Sox engaged in a classic World Series with the Reds but lost in seven, and again played without one of their young sluggers. Hall of Fame-bound rookie Jim Rice (.309, 22 HRs, 102 RBIs) — half of the “Gold Dust Twins” with MVP Fred Lynn — took a bone-cracking fastball to the hand on Sept. 22 and missed the World Series.

The 1986 Red Sox lost a seven-game World Series to the Mets, and some of us believe they would have won that series if not for a season-ending injury to Hall of Fame-bound Tom Seaver in early September.

Robert Williams has been a dominant defensive presence for the Celtics this season, averaging 2.2 blocked shots per game.Matthew J Lee/Globe staff

Seaver was not his Cy Young self in ‘86, but at 41 he gave the Red Sox 16 good starts after joining the team in July. His ERA was 3.80 and he pitched at least six innings in 12 of his 16 starts. He suffered a knee tear in the fourth inning of a game in Toronto Sept. 19 and never pitched again.

Seaver was on the shelf when the Sox were forced to start meatball artist Al Nipper in Game 4 at Fenway. Nipper, who had a 7.11 Series ERA, was beaten, 6-2, and the Sox lost in seven games.

Let’s not forget the 2008 Patriots. On the heels of their historic 18-1 2007 season, the Patriots watched in horror as Tom Brady got his knee taken out in the 2008 season opener and was gone for the year. With Matt Cassel at the helm, the Patriots went 11-5 but failed to make the playoffs for the only time from 2002-20.

The 2010 Celtics looked certain to beat the Lakers in the NBA Finals when they took a three-games-to-two series lead to Los Angeles for Game 6. But Kendrick Perkins’s knee collapsed in the first half of Game 6 and the Celtics dropped the final two games and lost a chance for Banner No. 18.

Now this. The Time Lord just had surgery. And Banner No. 18 is back on hold.