Sydney - Fading light forced the suspension of the Australia-Switzerland Davis Cup World Group playoff on Sunday, with Lleyton Hewitt and Stanislas Wawrinka into the final set of the deciding match.
Switzerland's Wawrinka was two sets to one up and leading 5-3 in the fifth when the match referee decided it was too dark to continue.
The two players will come back on Monday to complete the match, with Wawrinka leading 4-6, 6-4, 6-7 (7/9), 6-4, 5-3.
World No 3 Roger Federer earlier levelled the best-of-five tie at 2-2 when he beat Bernard Tomic in four sets 6-2, 7-5, 3-6, 6-3.
The winner of the tie will play in the top tier World Group in 2012, while the loser will be forced into regional qualifying.
The experienced Hewitt will have to win his first serve when play resumes Monday just to stay in the encounter.
Wawrinka struggled with injury and indifferent form in losing his opening singles match to Tomic on Friday, and then the doubles on Saturday.
But he put his troubles behind him to push Hewitt to the brink in what has so far been a magnificent display from both players.
Hewitt, who has been battling injury for some months, had not previously played in a live deciding rubber during his 13-year Davis Cup career, but looked in control as he broke Wawrinka in the first game of the match and held on for the set.
The Swiss world No 19 levelled proceedings with a single break of serve in the second set before Hewitt claimed the third in a tiebreak, saving four set points along the way.
Wawrinka would not be denied as he took the fourth, then broke early in the fifth to take control.
But with the match passing the two hour mark and the sun setting quickly on the Royal Sydney Golf Club venue, officials had no option but to call off play for the day.
Federer earlier used all his experience to see off the 18-year-old Tomic in a match played in warm conditions and swirling winds.
There were few expectations that Tomic would trouble Federer, who had beaten Hewitt in four sets on the opening day and was starting to find his feet on the low-bouncing grass surface.
Tomic had his chances in the opening two sets but Federer was able to take control at the key moments.
The young Australian, looking relaxed, claimed an early break in the third set and held on to keep the home fans interested.
The fourth set was something of a lottery in the conditions, but Federer's experience told in the end as he took the tie into a decider.