His first victories against top players happened in 1969 in Stockholm, where he defeated Tony Roche and Stan Smith.

In December, Năstase won his first Masters Grand Prix title, finishing in front of Stan Smith in a round robin competition.

Two months before, at Wimbledon, Năstase narrowly lost to Stan Smith in an epic[7] five-set final, one of the more exciting championship matches.

[8] In the Davis Cup, Năstase was undefeated in singles until losing to Stan Smith in the final played on clay in his native Bucharest.

In December at the year-end tour finals, Năstase defeated Smith, winning his second consecutive Masters Grand Prix title.

1 seed for the players in the subsequently weakened field and publicly stated his support for the ATP action but insisted that as a serving captain, he was under orders from the Romanian army and government to compete and thus could not boycott the tournament.

Some contemporary press speculation and later biographies have suggested Năstase contrived to lose his fourth-round match to American Sandy Mayer, but to have lost any earlier to a considerably less able player would have been too obvious.

For the fifth consecutive year, Năstase reached the Masters Grand Prix final in 1975, where he defeated Björn Borg in three straight sets.

In the second half of the year, third-seeded Năstase lost in straight sets to Borg in the men's singles final of Wimbledon and in the semifinals of the US Open.

[17] Shales called him "Năstase" when asking him to move to the advantage court, "like a master speaks to a naughty schoolboy.

[21] The British umpire George Armstrong refused to shake Năstase's hand as Ilie continued raving.

[21] In October 1977 at the Raquette d'Or tournament, Năstase used a 'spaghetti string' (double-strung) racket to end Guillermo Vilas's 46-match winning streak.

[24][25][26][27] In 1994 Năstase, Davis Cup captain of his country, was banned for an away match against Great Britain, for "'audible obscenities and constant abuse and intimidation of officials'" in a tie against South Africa.

[28] In 2017, while captaining his country's Fed Cup team against Great Britain, Năstase was overheard commenting about Serena Williams' unborn child, and the then 71-year-old asked Britain's Fed Cup captain Anne Keothavong for her room number while posing for photographers.

Before Great Britain and Romania began their two-day World Group play-off,[30] Năstase allegedly stormed in to the media centre to confront British journalists over the reporting of his comments the previous day.

Năstase could only find Press Association tennis correspondent Eleanor Crook before launching into a tirade about the reporting.

[31] During the second rubber, after the crowd had been told to respect the players, he said to match umpire Andreas Egli: "It's not the opera, what's your fucking problem?

[33] In a statement the International Tennis Federation (ITF) additionally confirmed that Năstase had his accreditation removed and would take no further part in the tie.

[35] When Năstase was ejected from the stadium he met Crook again and, separated by a large number of security guards, verbally attacked her.

[39] In a further interview with the BBC, Năstase justified his comments to Konta, stating that he only abused her after being ejected from the court and did so as a fan rather than a captain.

[41] The Madrid Open, however, invited Năstase to be part of the prizegiving ceremony, which was won by Romanian Simona Halep.

[42][43] Allegations of inappropriate behaviour included Pam Shriver claiming Năstase frequently asked in a joking manner if she was still a virgin.

[44] Dominique Monami, captain of the Belgium team, then mentioned that Năstase had abused her in the round before the match with Great Britain.

[46] Considered one of the most gifted tennis players in history,[47] Năstase was noted for his ability to entertain, amusing spectators with his antics and mimicry.

[48] Năstase pioneered a distinctive tennis shot, a backward, over-the-shoulder wrist-flick useful as a last resort in recovering lobs.

He entered Romanian politics in 1995, joining the Social Democracy Party of Romania[53] and making an unsuccessful run for mayor of Bucharest in 1996.

[citation needed] In 2010 he appeared in the "Be free" video of Smiley's band Radio Killer alongside footballers Ioan Lupescu and Ousmane N'Doye.