Reilly Opelka left to rue foul-mouthed tirade at umpire after coughing up two-set lead to Fabio Fognini

Big serving American Reilly Opelka has refused to blame his foul-mouthed tirade at chair umpire Carlos Bernardes for his first-round loss to 12th seed Fabio Fognini.

Fognini's hopes of advancing in the tournament looked as bleak as the weather on Day 1 of the Open as he found himself in a two-set hole before rain forced the match to be postponed.

However, Returning to 1573 Arena on Day 2, Fognini spectacularly turned the tables on his opponent, surging back to claim the match 3-6 6-7 (3-7) 6-4 6-3 6-7 (10-5).

Fognini was on the comeback trail on Day 2 when Opelka cursed at Bernardes for seemingly letting the Italian get away with time wasting after he was earlier hit with a code violation for the same thing.

"How many f---ing times are you going to let him get away with it?" Opelka could be heard saying as he approached the Brazilian umpire.

"You're f---ing pathetic. He's done it four times."

After the loss, Opelka downplayed the incident as something "normal" that happens during a match, but admitted that the "negative emotion" was not ideal when dealing with a combative opponent like Fognini.

"Especially against a guy like him. You want to keep him out of the match as much as possible," he told reporters.

"You don't want to engage with a guy like that. Definitely not a positive thing that's for sure.

"He was all over me at the time, I don't think that sparked him any extra. He came ready to play."

Fognini's win cemented his reputation as a comeback king of sorts, his seventh separate win at a Grand Slam event after finding himself down two sets, and Opelka was left to rue the drastic change of conditions between Day 1 and Day 2.

"It was different conditions and Fabio stepped it up today, which I was expecting," he said.

"The conditions today were a lot different. The temperature and less wind, I think that was the biggest factor. I actually would've taken today's conditions.

"Today was hot and fast and that's where I prefer to be but Fabio played well.

"(An interrupted match) is more difficult when you're two sets down than two sets up to be honest so that's what's a bummer about it."