Nick Kyrgios says he's disappointed Bernard Tomic has made himself unavailable to play for Australia this week as their fractious Davis Cup relationship continues.
Ahead of their world group tie against the Czech Republic at Kooyong starting on Friday, Kyrgios said he hadn't spoken to Tomic but couldn't see any reason why Australia's No.2 wouldn't make himself available to play.
World No.65 Jordan Thompson has replaced Tomic in the Australian team.
"We're not going to beg guys to play but it's disappointing not having him here as there's no reason why he shouldn't be here," Kyrgios said on Tuesday.
At the same time last year it was Tomic's turn to give Kyrgios a serve, accusing him of "faking" illness to skip the first-round tie in Melbourne.
World No.32 Tomic also questioned Kyrgios' ongoing commitment to Davis Cup, pointing to his withdrawal from their 2015 tie against the Czech Republic.
In response Australia's No.1 Kyrgios taunted Tomic on Twitter, referencing the Queenslander's 6-0 6-1 loss to Jarkko Nieminen in Miami in 2014.
"Let's not forget who holds the quickest loss on the ATP Tour lol," Kyrgios posted. "#howmanyminutesagain"
That tweet was later removed before Kyrgios followed up, saying that he wasn't going to "take it personally ... Just don't expect me to have your back anytime soon".
Tomic, who boasts a 17-4 win-loss record from 12 ties, said his withdrawal this time was due to scheduling issues although reports have surfaced of continued friction between the Tomic camp and Tennis Australia over funding for Tomic's younger sister Sara.
Kyrgios has a 4-3 win-loss record from five ties, making sporadic appearances since his debut in 2013.
After missing the 2015 first-round win over the Czech Republic in Ostrava, he was dropped for the reverse singles against Kazakhstan after losing to lowly-ranked Aleksandr Nedovyesov on day one in Darwin.
Kyrgios was then omitted from the semi-final against Great Britain in Glasgow following a turbulent month in the US punctuated by his unsavoury sledging of French Open champion Stan Wawrinka.