In 1988, Boris Becker dramatically beat Ivan Lendl in 5 sets in the Masters tournament at Madison Square Garden. The final set went to tie breaks, ending with a backhand net cord by Becker.
Have there been other major tournaments where the championship point was decided by a net cord shot?
Yes, there have been a few instances of the net cord deciding championship point in both the Men's and Women's tours:
ATP
Final - CA-TennisTrophy (Vienna) 2002, Roger Federer vs. Jiří Novák - The 21 year old Federer claimed his 8th title by striking a forehand which clipped the tape and fell on the side Novák.
6–4, 6–1, 3–6, 6–4
Final - Miami 2006, Roger Federer vs. Ivan Ljubicic - To cap off a thrilling final that went into a tiebreak all three sets, Roger ended it with a lucky net cord on the return.
7-6(5), 7-6(4), 7-6(6).
Final - Gerry Weber Open 2010, Lleyton Hewitt vs. Roger Federer - The three set final victory ended in a mid-rally net cord that fell the way of Hewitt at the gasp of the crowd. This victory broke a 15-match losing streak against Federer for Hewitt, and was the first time Federer had lost since 2002 in Halle.
3–6, 7–6(4), 6–4.
Final - Gazprom Hungarian Open 2018, Marco Cecchinato vs. John Millman - The net cord shot was struck by the eventual champion and 1st time ATP Tour tournament winner Marco Cecchinato.
7-5, 6-4.
WTA
Final - Wimbledon 1988, Steffi Graf vs. Martina Navratilova - In what proved to be a hard fought match, Graf pulled it out against then 6-time defending champion on a net cord return. Graf's slam victory proved to be a crucial one as it was the penultimate slam that enabled Graf to achieve the only Calendar Year Golden Slam in tennis history.
5–7, 6–2, 6–1.
Final - St. Petersburg Open 2019, Kiki Bertens vs. Donna Vekic - On her 4th championship point, Kiki Bertens was able to strike a backand that clipped the tape, and proved to be too great of a distance for Donna Vekic to run down.
7-6, 6-4.
