Tom E. Curran • E-mail

BOSTON - It’s time for Celtics coach Doc Rivers to hand the keys to point guard Rajon Rondo and say, "I’m going to bed. Be home at a decent hour. And I’ll be checking for dents in the morning."

Boston, leading the best-of-seven Eastern Conference semifinal series 3-2 after Wednesday’s 96-89 home victory, can make things (relatively) easy on itself by closing out the Cavaliers in Cleveland on Friday night.

Or the Celtics can go the other route Friday — face-plant on the road for the sixth time in these playoffs and come home to play the 14th game of their postseason against a slowly awakening LeBron James while the Detroit Pistons rest and wait.

Either way, Rondo earned the right to stop getting yo-yoed from the lineup in favor of calcified guard Sam Cassell on Wednesday night.

Playing 42 of the 48 minutes, the waifish Rondo scored 20 and added 13 assists, two steals and two blocks. The points came on drives, floaters and two massive 3-pointers in the second quarter. The bombs — and an assist to Kevin Garnett — rousted the Celtics and brought them back from a 43-29 deficit to trailing 43-37 in a two-minute span.

“I thought those were the two biggest shots of the game,” said sage Celtics veteran P.J. Brown. “He kind of grew up in front of us tonight. Young guys usually buckle in the pressure of the playoffs. He responded.”

The fear of buckling — and the unconventional style of Rondo’s offensive game — are the reasons Rivers has had a quick hook for Rondo in this series.

But the option Rivers has turned to — the 39-year-old Cassell — isn’t equipped at this point to deal defensively with the Cavs' speedy guards, Delonte West and Daniel Gibson. And Cassell’s penchant for looking for his own offense — usually from 23 feet away — isn’t well-suited for the long haul.

That came into clear focus Wednesday night. After Rondo had four points and five assists in the first quarter, Cassell started the second. A 23-18 deficit balloned to 35-22 with Rondo watching. Cassell missed both of the shots he took and had two assists and two turnovers in his 5:29 on the floor. That was one more turnover than Rondo had all night. And when Rondo returned, he brought with him a flow to the Celtics' offense.

That flow has been missing in all of the Celtics' previous five playoff road games where they’ve lost every time and scored 84 and 77 points in their two losses to the Cavs.

As much as the triumvirate of Paul Pierce, Garnett and Ray Allen has been the focal point of this Celtics team, none of them has really been able to replicate the steadiness of their regular-season performances for long stretches. Wednesday's game was the closest they’ve come — Pierce had 29 and Garnett 26 — but Rondo was the catalyst.

At some point, the Celtics are going to have to stop puckering offensively in the other team’s gym. This is a team that had the league’s best road record in the regular season. A regular season in which Rondo was given the latitude to run the team. Rivers’ apparent lack of faith in Rondo — or the trust he places in the veteran Cassell — was on display in the first four games of the series when Cassell played an average of 20 minutes and Rondo played about 28 minutes.

But Wednesday night — with James going off in Boston Garden for the first time in this series (35 points) — the Celtics were able to weather the storm with Rondo’s hand on the rudder.

“We’ve pretty much given him the keys all year,” Rivers said of Rondo. “Sam is struggling and the Gibson matchup was killing us with Sam.”

Gibson will be the least of the Celtics' worries when the teams get to Cleveland. Boston should expect another outburst from James in Game 6.

“Offensively, in the first half, we played extremely well,” James said. “We’ve just got to continue to get the ball from one side to the other and knock down shots.”

James has said the series won’t really begin until one of these teams wins a game on the road. Cavs center Zydrunas Ilgauskas smiled when reminded of that.

“It’s getting close to the end now,” said the 7-foot-3 center. “If we keep saying that, eventually the other team advances. (The Celtics) have a good cushion, being the best team in the NBA. They don’t have to win on the road (in the playoffs). We don’t win on Friday and we don’t have a game on Sunday.”

And if the Celtics don’t win Friday, they’ll be staring down the barrel of a megastar with their season on the line. It’s time now for Doc Rivers to dance with the skinny one that brought the Celtics to a 3-2 advantage. Rajon Rondo.

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