Borowiak played for Columbia University's sports department , the UCLA Bruins , and won the 1970 NCAA singles title in the final against Roscoe Tanner . The following year he won the NCAA double title with Haroon Rahim . He was also team captain of the team in 1970 and 1971. His teammate behind him in position 3 was Jimmy Connors , who won the NCAA singles title in 1971, also against Tanner in the final. Borowiak was named three times in a row in the top selection All-American from 1969 to 1971 .
He had been on the tour as a professional since 1968, where he could not show any great success in the first few years. Highlights include a round of 16 appearance at the 1970 Cincinnati Masters and a semi-final appearance alongside Haroon Rahim in the Pennsylvania Lawn Tennis Championships in Haverford , Pennsylvania . He reached his first individual final in Cologne in 1971 , where he was defeated by Bob Lutz in four sets . In April 1974 he won his first individual title at the WCT tournament in Charlotte , the second followed in the same year at the Oslo Open . 1977 was his most successful year with three individual titles, with victories in Dayton , Gstaad and his greatest career success, victory at the Canada Masters . In the final, he literally swept the Chilean Jaime Fillol 6-0 and 6-1 off the pitch. Borowiak competed with partners such as Ilie Năstase and Vitas Gerulaitis , most often he played with the Australian Dick Crealy . He won one of his three double titles in 1974 alongside Rod Laver .
In the course of his career he was able to win five singles and three doubles. He reached his highest ranking in the tennis world rankings in 1977 with position 20 in singles and in 1983 with position 303 in doubles.
His best individual result at a Grand Slam tournament was reaching the round of 16 at the Australian Open and at the Wimbledon Championships . It was the third round at the French Open and the US Open . In doubles he was in the round of 16 of the French Open and Wimbledon, he had the best result at the US Open in 1971, when he was in the quarter-finals with Haroon Rahim. In the mixed competition he reached the quarter-finals of the US Open in 1972 on the side of Pam Teeguarden .
Borowiak was friends with the Danish tennis player Torben Ulrich in the early 1970s , although he was significantly older. In addition to sport, both were very interested in music and musically: Both played together to their records, Ulrich the clarinet and Borowiak flute . Both remained friends even after their sports careers ended, and Borowiak acted as a financial sponsor of the band's son Lars Ulrich , which later became known as Metallica .
United States
Dick Stockton
Oslo
Karl Meiler
Buster Mottram
Gstaad
Jean-Francois Caujolle
Canada Masters
Jaime Fillol
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Osaka