Right-hander Roger Clemens struck out a major league record 20 batters and pitched a three-hitter tonight in the Boston Red Sox' 3-1 victory over the Seattle Mariners.

Clemens (4-0) walked none and allowed only a seventh inning homer by Gorman Thomas and singles to Danny Tartabull and Spike Owen on his way to his second complete game this season.

"I was trying to keep it close, trying to battle a guy that's throwing a good game against us," said Clemens, who threw 138 pitches -- 97 for strikes. "The strikeouts just kept on coming. I knew something was happening because of the way the fans were reacting."

The 20 strikeouts broke the record of 19 shared by Steve Carlton (St. Louis Cardinals, 1969), Tom Seaver (New York Mets, 1970) and Nolan Ryan (California Angels, 1974). Washington's Tom Cheney struck out 21 in 16 innings against Baltimore in 1962.

Clemens, who struck out 14 over the first six innings, including an American League record-tying eight in a row, tied the record by striking out Owen to open the ninth. He then struck out Phil Bradley for the fourth time to establish the record before getting Ken Phelps to ground out for the final out.

"I've seen Catfish Hunter pitch a perfect game and I've seen Mike Witt pitch a perfect game, but that has to be tops," said Boston Manager John McNamara. "This has to be the most awesome piece of pitching I've seen."

In 15 games last season, Clemens struck out a total of 74 in earning a 7-5 record and 3.29 ERA.

Clemens, 23, tied the AL record with eight consecutive strikeouts from the fourth to sixth innings before Owen flied out to center field. The mark was first set by Ryan in 1972 and tied by Ryan in 1973 and by Ron Davis (New York Yankees) in 1981.

Seaver set the major league record with 10 straight strikeouts against the San Diego Padres in April 1970.

Thomas' home run with two outs in the top of the seventh gave Seattle a 1-0 lead. But with two out in the bottom of the inning, Steve Lyons singled to left, then Glenn Hoffman was walked by Mike Moore (1-2). Ed Romero ran for Hoffman before Dwight Evans hit a 1-0 pitch into the center field seats, putting Boston in front, 3-1.

"After Gorman put the ball in the stands, it was a case of battling back," Clemens said. "Then when Dwight popped it, that gave me a second wind."