Who did John McEnroe beat in his first match on the way to winning his first Wimbledon title?

John McEnroe defeated his rival, the five-time defending champion Björn Borg in the final, 4–6, 7–6(7–1), 7–6(7–4), 6–4 to win the Gentlemen's Singles tennis title at the 1981 Wimbledon Championships. Borg was attempting to equal William Renshaw's sixth consecutive Wimbledon title and Roy Emerson's all time record of 12 Grand Slam titles.

It was this tournament where John McEnroe shouted the now-famous "You cannot be serious!" to the chair umpire in response to a serve being called "out." The disagreement took place on June 22 during the first round match against Tom Gullikson. McEnroe beat Gullikson 7-6 (7-5), 7-5, 6-3.

Tom Gullikson (born September 8, 1951) is a tennis coach and former professional tennis player born in La Crosse, Wisconsin and raised in Onalaska, Wisconsin in the United States. During his career as a player, Gullikson won 16 top-level doubles titles, ten of them partnering with his identical twin brother, Tim Gullikson, who was also a noted coach. Tim coached the then number one player in the world Pete Sampras before Tim was diagnosed with brain cancer in 1995, and died in 1996. The brothers were runners-up in the men's doubles competition at Wimbledon in 1983. Gullikson also won the mixed doubles title at the US Open in 1984, with Manuela Maleeva.