The true meaning of the word relentless can't be found in points scored, but in doing what must be done when it has to be.

Perhaps that is why the Milwaukee Bucks, who were facing as close to a must-win situation as a team can, emerged with a 109-104 victory tonight at the Spectrum in Game 4 of their NBA Eastern Conference semifinal series against the Philadelphia 76ers.

Now tied at 2-2, the teams will meet again Wednesday night at the Mecca in Milwaukee, with Game 6 Friday in Philadelphia.

In winning their first postseason game here in four years, breaking an 0-6 streak, the Bucks were paced by Terry Cummings and Ricky Pierce with 19 points each.

Philadelphia's Charles Barkley continued his string of irrepressible performances with a career playoff-high 37 points, 14 rebounds and nine assists. He made 11 of 17 field goal attempts and went 15 for 19 from the foul line.

The power forward provided the evening's most outstanding play when, early in the third quarter, he saved the ball from going out of bounds, hurtling the 76ers' bench and falling into the crowd in the process.

Imagine the Bucks' surprise seconds later when the 6-foot-6, 250-pounder came barreling through the lane just in time to receive a pass and finish the effort with a thunderous slam dunk.

That was the level both teams played at for the entire game. There were 42 ties and lead changes, with neither squad moving up by more than eight points. There were also 19 blocked shots and 10 three-point plays.

"We had to win," said Milwaukee center Alton Lister. "That's what it's all about."

There was, however, more than a little doubt about the outcome of the game until the final moments, when the last and most important of the three-point plays occurred.

Despite having some semblance of control, moving ahead by 93-86 with 8:28 to play, the Bucks were aghast to see the 76ers roaring back for the fourth time in four games.

By the 3:51 mark, Philadelphia's deficit was 99-98 after guard Maurice Cheeks stripped the ball from Craig Hodges and converted a pair of free throws after being fouled.

Fifteen seconds later, the Bucks' Paul Pressey, who scored nine of his 17 points in the final period, was fouled but missed both his free throws. Given a sliver, Barkley thundered through it, driving the lane for a basket and free throw after being fouled to put the 76ers up, 101-99, with 3:23 left.

"It seems like all our games are like that," said 76ers forward Bob McAdoo, who scored 17 points. "We'd like to be in the driver's seat. I'd like to have a 10-point lead going into the last minute."

Indeed, the mere deuce wouldn't suffice. Taking a timeout immediately after Barkley's play, the Bucks put the ball in the hands of Sidney Moncrief, who once again provided the team with an emotional lift, playing 38 minutes and scoring 13 points despite a torn tissue in his left foot.

This time, the all-star guard's shot fell short, but it went right into the hands of Pierce, who threw the rebound into the basket while being fouled. The subsequent free throw gave the Bucks a 102-101 advantage, but the 76ers tied the score on Cheeks' free throw.

Leading, 106-104, with less than two minutes to play, the Bucks got the breaks that seemed to elude them in their 107-103 loss in Game 3.

Pressey nearly lost the ball to Barkley while dribbling into a corner, then his pass into the low post was tipped away by Sedale Threatt. Somehow, after a flurry of flailing hands, the ball found its way back into Pressey's hands and the swingman made a hook shot from the lane to ensure the victory for Milwaukee.

"We had the crowd 17,941, the 76ers' first postseason sellout this year goin' crazy, pumping us up," said Barkley. "You gotta give the Bucks credit. We're not playing horseshoes; nothing matters but the final score."

And for coming out on the front end of that all-important statistic, the Bucks can credit a kind of tenacity that was epitomized by Moncrief.

"I can't recall any time since I've played basketball that I've had to maintain play through such pain," he said. "If it were the regular season the chances of me playing would be slim, but this is the playoffs.

"I'm not so sure if all the attention and hype is overstated, but for me the most important thing to do in the playoffs is advance. The idea is just to keep winning at all costs."