Johannesburg - South Africa's potential Davis Cup relegation problems were heightened on Thursday when the country's third-ranked Izak van der Merwe revealed he would be unavailable for all the remaining ties this year because of a persistent right ankle and heel injury.
South Africa are due to meet Slovenia in an away tie starting on September 13. If they lose that they face a further match-up against Russia in October.
A defeat against Russia, who boast six players among the top 100 in the world, including 27th-ranked Mikhail Youzhny, would send South Africa plummeting out of the Euro-Africa Group One segment of the Davis Cup into Group two.
"It's been steady, but slow progress since I suffered the serious injury in an ATP Challenger tournament in March," said Van der Merwe from Virginia Beach in the United States, where he is recovering under the guidance of a physiotherapist and fitness trainer.
"I've been granted a protective ranking by the ATP because of the injury. But I won't be ready to play in the Davis Cup in either September or October, with my handlers indicating I might be able to return to tournament tennis in November.
"I'm deeply sorry I won't be around to help the South African team during this vital period and hopefully I'll be able to rejoin the squad in 2014."
Van der Merwe's unavailability means Davis Cup relegation is now looming larger, with top player Kevin Anderson giving no indication of ending his recent embargo of the event against Slovenia.
Tennis SA CEO Ian Smith and Davis Cup captain John-Laffnie de Jager have confirmed that no word had been received from Anderson regarding his availability. This was despite a request made several months ago that he should make his intentions clear.
With the world's 21st-ranked Anderson included, South Africa would have more than a fighting chance of avoiding defeat against Slovenia and eliminating any chance of a humbling drop to Euro-Africa Group Two.
However with Anderson an absentee and the Slovenian squad of Grega Zemlja, 55th in the world, Aljaz Bedene (106th), and Blaz Kavcic (120th) enjoying home-court advantage and all ranked infinitely higher than South Africa's next best Rik De Voest on 163rd, the odds will swing heavily in favour of the East Europeans.
And defeat against the Slovenians would mean South Africa facing an even tougher must-win away tie against Russia.
"There is nothing further I can say about Kevin Anderson playing or not playing because we have not heard from him," Smith said.
De Jager said he had not personally contacted Anderson.
"The ball is clearly in his court to provide us with his decision. Obviously without him in the team it would be a massive blow, but either way, we have to be positive in a do-or-die situation."