(SportsNetwork.com) - The defending champion San Antonio Spurs return home from an up-and-down road trip on Friday to host the Boston Celtics at the AT&T Center.

The Spurs opened their two-game road trip with an ugly overtime loss to the New York Knicks on Tuesday, but got things back on track Wednesday with a 114-103 victory over the Milwaukee Bucks.

Danny Green had 20 points and eight rebounds to pace the Spurs. Tim Duncan posted 19 points, seven assists and five boards, while Boris Diaw added 18 points, six rebounds and five helpers for San Antonio, which is 2-2 since a six-game winning streak.

"We shot the ball better and played much better defense. It is what we expect from our team," Duncan said.

After a Michael Carter-Williams reverse layup pulled the Bucks within 51-49 at the 3:04 mark of the second quarter, San Antonio ripped off eight straight points for its first double-digit lead of the game.

The Spurs led 63-54 at the break and were up by as many as 19 in the third before settling for a 91-80 margin heading into the fourth. Milwaukee never got within less than nine in the final frame.

The Spurs, who are seventh in the west, but one game behind fifth, are back on the road, starting Sunday against the Eastern Conference-leading Atlanta Hawks. They play the Dallas Mavericks in Big D on Tuesday.

The Celtics saw an end to their five-game winning streak on Wednesday. Boston is tied for the eighth seed in the Eastern Conference with the Indiana Pacers, a game behind the Miami Heat and a half-game ahead of the Charlotte Hornets.

The Celtics couldn't handle the Oklahoma City Thunder and fell, 122-118, at Chesapeake Energy Arena. Russell Westbrook recorded 15 points during a third quarter in which Oklahoma City outscored Boston by a 40-24 margin, then put up 10 more in the fourth to help the injury-plagued Thunder to an important win.

Boston received a career-high 25 points and nine rebounds from Marcus Smart. Kelly Olynyk and Brandon Bass each tallied 20 points in defeat.

The Celtics cut their deficit down to four, but the Thunder responded with a 13-1 flurry that overlapped into the opening two minutes of the fourth quarter. Oklahoma City forced three turnovers and went 7-of-7 from the foul line during the sequence, which had the home team up by a 97-81 count.

"We didn't balance poise and assertiveness in what we do well," said Celtics head coach Brad Stevens. "It's a fine line. Credit (Oklahoma City)."

Boston did battle back and managed to pull within 108-103 after a 12-3 stretch that ended in back-to-back treys from Smart and Olynyk, the last coming with 2:30 left. The Celtics managed just two free throws on their next four possessions, however, and Oklahoma City stretched the lead to 11 before holding on in the closing moments.

The Spurs beat the Celtics by 22 in Boston on Nov. 30 and have won six straight in the series. San Antonio has taken two in a row as the host after the Celtics had won five straight.