Eighth seed Stanislas Wawrinka saw off the dogged challenge of Colombia's Alejandro Falla to advance to the third round of the Australian Open.
In what was the final match of the evening session on Margaret Court Arena, Wawrinka did not have things all his own way but eventually came through 6-3 6-3 6-7 (4/7) 6-4 in a little over two and three-quarter hours.
The Swiss No 2 dominated the opening couple of sets; one break in the first and two in the second saw him take control of the contest with Falla unable to make much impact on his opponent's delivery.
He looked on course for a straight sets triumph as he broke first in the third, but Falla showed real determination to battle back and force a tie-break.
In it he secured a mini-break from the first point which was to prove decisive as he stayed strong on serve to take the match into a fourth set.
Having broken to move 2-1 ahead, Wawrinka looked in charge once again, but Falla refused to go away and broke back to level at 3-3 after his rival netted a forehand.
Moved up a gear
But Wawrinka moved up a gear in the ninth game; a superb slice backhand clipped the line to bring up two break points and he took the first when Falla charged in behind a serve and found the net with a regulation volley.
Wawrinka needed no second invitation and duly served out to love to clinch victory and will next face 28th seed Vasek Pospisil of Canada after he came from a set down to beat home hope Matthew Ebden 3-6 7-6 (8/6) 7-6 (11/9) 6-1 on Rod Laver Arena.
Like Wawrinka, fellow seeds Fabio Fognini (15), Tommy Robredo (17), Jerzy Janowicz (20) and Jeremy Chardy (29) all needed four sets to get past Jarkko Nieminen, Julien Benneteau, Pablo Andujar and Alexandr Dolgopolov respectively.
19th seed Kevin Anderson was a 6-4 6-3 6-4 winner over Austria's Dominic Thiem, while France's Edouard Roger-Vasselin overcame Spain's Guillermo Garcia-Lopez in four.
Two more seeds bit the dust as Sam Querrey ousted Ernests Gulbis and Denis Istomin got the better of Dmitry Tursunov.
In the battle of the big serves, Querrey recorded a surprisingly facile 6-2 6-3 6-4 triumph, while Istomin proved too strong for his Russian opponent with a 7-6 (7/3) 4-6 6-1 6-4 success.