It was the left-hander's first success in seven matches against the Wimbledon champion. Perhaps the reddish hue of the indoor carpet court reminded the French Open champion of the clay on which he has won all but one of his 34 singles titles.
In the final today, Muster will face another American, the unseeded MaliVai Washington, who beat Agassi in the third round and Sweden's Thomas Enqvist in the quarter-finals, yesterday beat Arnaud Boetsch, of France, 7-5 6- 2. Last week, Muster defeated Washington in the first round in Vienna.
A strained chest muscle has denied Agassi the opportunity to defend the Paris Indoor title next week, after which Sampras will overtake him on the computer, setting up a showdown for the year-end No 1 ranking at the ATP Tour Championship in Frankfurt on 14 November.
Muster, who is known in Germany as "Alpine Boris", is not the type of opponent to beckon into a match after dictating the opening points, which is the mistake Sampras made. The Californian led 4-1 - having missed an opportunity which would have made it 5-0 - and was then 4-1 ahead in the tie-break.
In both cases, Sampras betrayed sufficient signs of slackening his tempo for Muster to attack his serve and begin to draw him into rallies. Although the American produced an ace to save a set point at 6-5 in the tie-break, Muster outmanoeuvred him to create a second, whipping a forehand pass after Sampras hit a backhand volley when the ball seemed destined to drift wide.
Muster showed his delight by shaking a fist in triumph close to the face of the baseline judge, having skidded to a halt in front of his chair at the end of the rally. Sampras then netted a weak backhand service return to lose the shoot-out 8-6.
Three consecutive breaks of serve turned the second set. Sampras double- faulted for 1-3, but then lured his opponent into netting a forehand for 2-3. Muster proceeded to win the concluding 11 points from 15-15 in the sixth game, his one stroke of fortune being a net cord which deflected the ball over Sampras's racket the break point for 4-2.
"Thomas clawed his was back and I got a bit frustrated after I lost the first set," Sampras said. "He fought hard and deserved his win today. He was hitting the ball extremely heavy and extremely deep and surprised me with his returning. He's had a tremendous year on clay and has proved he can win on indoor surfaces.''
Muster is attempting to win his 12th title of the year, and his first ever indoors. His one success other than on clay was on a rubberised concrete court in Adelaide in 1990, which marked the first triumph of his comeback after being injured by a drunk diver in Florida in 1989.Reuse content