But what turned out to be a relatively easy start to a five-game road trip gets decidedly tougher starting Monday.
Boston beat Milwaukee 99-77 as Allen sat at the end of the bench in a suit after injuring his heel the night before. Allen could return as soon as Monday -- and the Celtics will need him, as they face a brutal stretch of games at San Antonio, Houston, Dallas and New Orleans.
"These are going to be playoff-style basketball games," said Kevin Garnett, who scored 19 to lead Boston. "We have to be ready. We've got a long road trip, so it's good to get this first one and try to carry it on."
Even without Allen, the Celtics had no problem rebounding from a home loss to Utah on Friday. Eddie House scored 17 -- all but two in the second half as the Celtics were able to empty their bench -- and Paul Pierce and Rajon Rondo added 13 apiece.
Pierce and Garnett both rested the entire final quarter.
With the victory, Boston has won 11 of its last 12, including five straight on the road. But the previous night's 18-point loss to the Jazz still was on players' minds.
"We really buckled in on the defensive end," Pierce said. "I knew we weren't going to come out flat. It was a good win in a back-to-back, especially after the way we played last night."
The Celtics held the Bucks to 34.1 percent shooting from the floor, just above its season low of 32.9 percent set in a Nov. 3 victory over Chicago. Milwaukee was 5-for-26 from 3-point range.
Charlie Bell scored 16 to lead Milwaukee, which has lost five straight and eight of its last nine. Bucks coach Larry Krystkowiak acknowledged his team's shooting woes, but seemed more concerned about a defense that seems to be getting worse.
"With the season not going the way we'd like it to go, we're not out there being real proactive and making plays and filled with a lot of energy," Krystkowiak said. "I think at this level, we're talking about milliseconds in terms of reaction. We just don't quite have that reaction and the pep in our step that we need to have."
That wasn't a problem for the Celtics, even when their backups were on the floor.
Backup guard Tony Allen started in Ray Allen's place after the All-Star slipped and fell in the first quarter of Friday's game, causing an injury Celtics coach Doc Rivers called "nothing serious."
But it was veteran guard Sam Cassell, a recent addition to the roster, who made a bigger splash as Boston took control early in the second quarter.
Leading by 3, the Celtics went on an 18-6 run that included three jump shots by Cassell, who started the game 4-for-4 from the floor.
"It's just a matter of time for me to be real comfortable," said Cassell, who signed with Boston as a free agent March 4. "I'm comfortable right now, but I'm not where I want to be right now. Three or four more games and I should be fine."
The Celtics went into halftime leading 53-35 after an 8-2 run in the final 1:35 of the second quarter. Rivers was happy that his second unit built the Celtics' lead instead of giving it up, and credited another recent free agent addition, P.J. Brown, for cleaning up his team's early rebounding problems.
"Sam had the offensive going, but I thought P.J. was just really impressive," Rivers said.
The Bucks couldn't mount a comeback in the third quarter, and Rivers played his subs in the fourth. James Posey dunked off a long outlet pass from Brian Scalabrine with 3:56 left in the game, putting Boston up 85-66.
"You look at them and they don't have Bogut and they don't have Yi, so you have to try to take advantage of that," Rivers said.
Mo Williams and Desmond Mason returned to the starting lineup from injuries for Milwaukee. Williams scored five points on 2-for-6 shooting, and Mason scored 8. ... Krystkowiak said Yi is feeling better, and is optimistic both he and Bogut will return in the upcoming week.