Evonne Goolagong rose to No. 1 on the WTA rankings on this day 50 years ago

Fifty years ago to this day, on April 26th, 1976, Evonne Goolagong rose to No. 1 on the WTA rankings for the first time after winning the Virginia Slims Championships—now known as the WTA Finals—which were held in April that year.

Except she didn’t.

In a one-of-a-kind situation in tennis history, the only one we now know of, anyway, Goolagong’s rise to No. 1 wasn’t discovered for another 31 years, in 2007, when the WTA found several paper records missing in their rankings archive, and discovered that the Australian had overtaken Chris Evert for the top spot for two weeks from April 26th to May 9th, 1976.

WTA rankings were calculated every two weeks at the time.

And so, although she was the 16th player ever to be announced as No. 1 on the WTA rankings, Goolagong was in fact the second woman ever to do it, after Evert.

The seven-time Grand Slam champion would finally receive her WTA No. 1 trophy in 2007, not just 31 years after actually rising to the top spot, but 24 years after retiring from the tour.

“I’m very proud of the achievement,” Goolagong told the Associated Press in 2007. “I was on a roll for that stretch in 1976. It was a great surprise to hear after all these years.”

The WTA rankings were still in their early stages when Goolagong’s No. 1 omission occurred, having only been introduced five months earlier in November of 1975.

“Unfortunately our record-keeping wasn’t perfect in those early days of women’s tennis and our ranking system was viewed as a means of just accepting tournament entries,” then-WTA CEO Larry Scott said at the time. “It wasn’t until the early 1980s that the media and players started to pay attention to the changes in the rankings during the year as opposed to only the end-of-season rankings.”

In the end, though, Goolagong was rightfully recognized as a world No. 1, just the latest addition to an already-historic resume that included seven Grand Slam titles—four Australian Opens in 1974, 1975, 1976 and 1977, one at Roland Garros in 1971 and two at Wimbledon in 1971 and 1980.

She also won her last two majors—the December Australian Open in 1977 and Wimbledon in 1980—as a mom, one of only three women to achieve the feat in the Open Era, alongside Margaret Court and, more recently, Kim Clijsters.

She’s the only mom to win Wimbledon in the Open Era.

She also won six majors in doubles and one in mixed doubles.