Andrey Rublev has been defaulted from the Dubai Tennis Championships semifinals for unsportsmanlike conduct after yelling at a line judge in the final set of a tense encounter against Alexander Bublik. 

In a chaotic match where both competitors fumed at the officials at various points, Rublev was defaulted by the chair umpire after a Russian-speaking official appeared to accuse him of using an obscenity, while he screamed at the line judge.

Rublev denied the allegation and said he had spoken in English during the confrontation.

A confused Bublik, who clawed his way back from a set down to lead 6-7(7/4), 7-6(7/5), 6-5, was awarded the win despite saying that he would be happy to continue the match.

The Russian-born Kazakh had fought back from 4-2 down in the decider, adding to the frustration of his childhood friend, who lashed out at the line official at the change of ends after disagreeing with a call.

Another official, who spoke Russian, then confronted Rublev and appeared to accuse him of swearing at the line judge in his mother tongue, which the world number five vehemently denied.

But after a lengthy back-and-forth, the 26-year-old was disqualified.

"I highly doubt Andrey said something crazy. He's not this kind of guy. But I guess that's the rules. That's what they did, they just follow the procedure," Bublik told reporters.

"There's not much to say. With all due respect, it was a great match and both of us deserved to win.

"I wish Andrey to get back on track as soon as possible."

The result meant that Rublev will lose his prize money and ranking points earned at the tournament and that there would be no repeat of last year's title clash where he was beaten by fellow Russian Daniil Medvedev.