Pete Sampras defeated longtime rival Andre Agassi, 6-1, 7-5, 6-4, today to win the ATP Tour World Championship title and end the decade that he has dominated in superb style.

Sampras was at his best after being hindered by injury much of the year, outplaying the opponent who replaced him as the world's No. 1 when he was sidelined with back problems.

The Wimbledon champion equaled Ivan Lendl's record of five titles in the season-ending event and will move two places to third in the year's final rankings. Sampras finished 1998 as No. 1 for a record sixth consecutive year.

Sampras played one competitive match in the three months before this lucrative tournament and lost to Agassi, 6-2, 6-2, in a round-robin group match this week. But he delighted 13,000 fans with an attacking style reminiscent of his defeat of Agassi in this year's Wimbledon final. Sampras earned $1.38 million. Agassi, who will end the year at No. 1 for the first time after winning the French and U.S. opens, earned $800,000. "Andre has had a great week," Sampras said. "I was able to play my best tennis today. I think the match was of a very high level. . . . He deserves to be the number one."

Sampras was on from the start and won the first set in 27 minutes. But Agassi briefly looked as if he might rally when he opened a 3-0 lead in the second set. However, Sampras broke back and took the set when Agassi hit a forehand long.

The end neared for Agassi, who won the tournament in 1990, when he dropped serve in the opening game of the third set.

Sampras maintained the pressure, sealing an impressive performance with an ace on his first match point after 1 hour 46 minutes.

It was the 28th meeting in the series. Sampras leads the series 17-11.

After 10 years in Germany, including four in Hanover, the tournament will move to Lisbon in 2000 and Sao Paulo, Brazil, in 2001.