Andy Murray could have to play twice on Saturday after his Davis Cup singles match against Andreas Seppi in Naples was suspended because of bad light.
The Briton led 6-4 5-5, after Fabio Fognini had earlier given Italy the lead in the quarter-final with a 6-4 2-6 6-4 6-1 win over James Ward.
Heavy rain had delayed the start of play by over two hours.
Murray and Seppi will resume at 10:00 BST on Saturday, with the Scot then potentially involved in the doubles.
Colin Fleming and Ross Hutchins are the nominated doubles team, but British captain Leon Smith will be tempted to call in his top player for what could be a crucial third rubber in the best-of-five tie.
"It makes it more complicated because we'd rather be sitting here at 1-1, with Andy done and dusted and able to rest in the morning," said Smith. "Now he's got to get ready for a very early start.
"First and foremost we've got to get Andy focused to finish the job against Seppi, which is a very, very difficult challenge. But Andy, I think, is in the driving seat now.
"Once that match is finished it's about having a discussion with Andy and the rest of the team to see what we do about the doubles."
Murray, who was laid low by a stomach bug on Thursday, had to save four set points in the gathering darkness against Seppi on Friday, and has lots of work still to do if he is to draw Britain level on Saturday morning.
The late finish was a result of Friday's opening singles rubber being delayed by heavy rain, and the groundstaff's subsequent attempts to clear the standing water leading to areas at the back of the court being flooded.
Fognini was unhappy with the damp patches and divots churned up in the loose clay behind the baseline, and in the following match Murray almost rolled his ankle as early as the second point in the same area of the court.
After a slow start, Fognini recovered from 3-0 adrift to take the opening set of the first rubber before Ward's power hustled the world number 13 out of the second.
Ward, who beat then-world number 45 Sam Querrey in Great Britain's first-round win over United States in February, fought valiantly, and Fognini roared in relief as he faced down two break-back points in the final game of the third.
"I played well," said Ward. "I had to play well to play a guy like Fabio on clay who, for me and I'd say most people, is top three in the world at the moment."
The support of a sizeable contingent of British fans could not carry world number 161 Ward back into the match as Fognini's crisp hitting from the back and touch at the net brought home the fourth set.
Murray began the second rubber knowing victory was vital for for British hopes, and that the match was unlikely to finish before darkness fell.
If the Wimbledon champion's season has yet to really get going after back surgery last September, Seppi has won just four matches in 2014 and has a 1-5 record against Murray.
The 30-year-old Italian, ranked 34th, matched Murray for the most part, but the world number eight got the decisive break in game seven as he took the first set.
Both players knew that the second set was almost certain to be the last of the day, and Seppi broke at the fourth opportunity to lead 4-2, only for an irate Murray to hit straight back in the following game.
With the sun dipping behind the stand, Murray saw three chances to break again slip by at 4-4 and, after a discussion between the team captains and the umpire, it was decided there would be one more game.
The pressure was on Murray to hold serve in the gloom, and he fended off four set points in a dramatic game to level at 5-5 and set up a tense start on Saturday.