Sampras, who guided the United States to their Davis Cup triumph last weekend despite an attack of cramp, can increase his earnings in the world's richest tennis event to $2.12m by winning the cup.
The Wimbledon champion won the first set against McEnroe with ease. Although his form slipped slightly in the second, Sampras used his big serve to maximum effect on the fast indoor surface to take the tie-break 7-1. In fact, Sampras had more trouble with a nosebleed than with his opponent.
There are no rankings points at stake at the Munich tournament, which brings together the 16 best performers from the four Grand Slams - Wimbledon and the US, French and Australian Opens.
However, the huge amounts of money on offer persuade many players to postpone their end-of-year holiday following last month's ATP Tour world championship. Sampras has earned a bonus of $500,000 just for turning up in Munich after victories at Wimbledon and the US Open. The losers in the quarter-finals - the next round for Sampras - are guaranteed $262,500, while the eventual winner's prize is $1.625m.
But the American admitted afterwards that he had no major expectations from the tournament after the energy-sapping Davis Cup victory against Russia. "I still feel tired, mentally and physically," Sampras said. "I have no great expectations here. I have come here thinking: 'If I can play well, then good. If not, then I'll go home and it's been a good year'."
In the quarter-finals, Sampras will play another big server, Goran Ivanisevic of Croatia.
The American Todd Martin booked his place in the quarter-finals with a 7-6, 6-4 victory over Spain's former French Open champion, Sergi Bruguera.Reuse content