Bigger help may be on the way, but last night the Celtics made desperation work for them. A fatigued Kevin Garnett was given the night off — Doc Rivers said he should have given his center a rest two nights earlier against the Lakers — and the result was one of the smallest Celtics teams in memory. Consider the C’s lineup that opened the second half of last night’s 113-88 win over Phoenix, their biggest margin of the year: Paul Pierce (6-foot-7), Brandon Bass (6-8), Jeff Green (6-9), Avery Bradley (6-2) and Courtney Lee (6-5). The Celtics coach, with one of the Western Conference’s worst teams on the other side, was able to work new combinations. He got a lengthy 25-minute look at Terrence Williams, who was once told by his Louisville coach, Rick Pitino, to take advantage of his Paul Pierce video library. Rivers was pleased with the swingman’s nine-point, four-rebound, four-assist performance. The 6-foot-6 Williams played everything from small forward to point guard. The even-newer Jordan Crawford was sent in to do what he does best — shoot the ball — and finished with 10 points in 18 minutes. But Jeff Green, given his first start of the season as the result of Garnett’s absence, led this speed lineup with 31 points on 11-for-14 shooting — his high as a Celtic. “Jeff was fantastic,” said Rivers. “He knew he didn’t play well against the Lakers. He was down after that game, and he voiced that.