[4] Although she had won a bronze medal in singles for Norway at the 1912 Summer Olympics in Stockholm,[5] and was the many-time champion of her homeland, Mallory was relatively unknown when she arrived in New York City to begin work as a masseuse in 1915.

She entered the U.S. Indoor Championships that year unheralded and beat Marie Wagner 6–4, 6–4, which was the first of her five singles titles at that tournament.

Mallory had less in the way of stroke equipment than most tennis champions, but she was a fierce competitor, running with great endurance.

"[6] Therefore, she relied on her baseline game, consisting of strong forehand attacks and a ceaseless defense that wore down her opponents.

"[6] Her second-round match with Suzanne Lenglen at the 1921 U.S. National Championships brought Mallory her greatest celebrity.

[1] Before the match, Bill Tilden advised Mallory to "hit the cover off the ball."

The French Tennis Federation (FTF) exonerated Lenglen and accepted her testimony (and a doctor's) that she had been ill.

He claimed that Lenglen was "perfectly fit" during the match and that, "She was defeated by a player who on that date showed a better brand of tennis.

This was to remind Mallory that she – Lenglen – had indeed had whooping cough in their New York match the previous year.

In 1926, Mallory hit one of the heights of her career when she came back from 0–4 in the third set of the final against Elizabeth Ryan, saving a match point in winning her eighth championship.

The World Hard Court Championships (WHCC), actually played on clay in Paris or Brussels, began in 1912 and were open to all nationalities.