'Locked in' Tiafoe leading American charge at Australian Open

Tiafoe saw off Chinese teenager Shang Juncheng with a 6-4 6-4 6-1 victory to advance to the third round while his United Cup team mates Jessica Pegula and Madison Keys also moved to the third round in the women's draw.

The American players have been talking about being "locked in" this week in Melbourne and have even drawn pictures of locks on a television broadcast camera using a marker pen following their wins.

When asked about the mantra, Tiafoe told reporters: "It's the whole thing with the United Cup guys, just staying locked in. I made a joke about it with the guys (at) the United Cup asking them before the match, 'Are you locked?'

"The locked thing, honestly, I've been kind of living by that for a little bit. I think you've seen the shift in myself in being just locked in everything you're doing, staying super present, staying in the moment, staying locked in.

"It's funny coming from me because everyone knows how I go about my business. I'm very open and just joking around. When I'm saying it, it just sounds funny. So then it became a thing where if Frances can lock, everyone has got to lock."

Taylor Fritz's attempt to draw a lock following his first-round victory went horribly wrong and Tiafoe did not shy away from mocking his compatriot having played pranks on him at the United Cup.

"Fritz, dumb ass drew a penis the other day trying to draw a lock sign. That's Fritz being Fritz," Tiafoe said.

Fritz clarified on Twitter that he was trying to draw the lock emoji, saying: "I just forgot the very important fact that I suck at drawing."