Belinda Bencic apologises for US Open outburst

Belinda Bencic admitted she must work on her on-court emotions, after being reduced to tears before pulling out a comeback victory at the US Open.

The Swiss star was down 0-40 in the 12th game of the second set against Misaki Doi, but emerged a 5-7 7-6 (7-2) 6-3 winner at Flushing Meadows - earning a clash with two-time winner Venus Williams.

Bencic was reduced to tears just prior to going down match point, and was seemingly bound for defeat.

Regardless of her Houdini-like escape, the teenager apologised for her conduct on Twitter - she had previously shown her frustration at the line judges and chair umpire - and said she would work on controlling her emotions.

"I was really mad. I was just so frustrated today. I think we all have not-so-good days, but I was very frustrated for the line calls and the referee," Bencic told a news conference.

"I know I shouldn't have behaved like that. For sure I know that.

"But sometimes I just can't control myself right now.

"I for sure have to be working on that, but I think I'm not the only one who would freak out like this."