Wellington - David Ferrer put last week's Doha disappointment behind him with a comfortable straight-sets win in his opening match at the Auckland Classic on Wednesday.
The 6-2, 6-4 victory over Australian qualifier Matthew Barton put the top seed and four-time champion into the quarter-finals to face Czech Lukas Rosol, a surprise winner over fifth seed Benoit Paire of France.
Ferrer had rushed to Auckland for a wildcard entry after his opening-round loss to Ukraine's Ilya Marchenko in the Qatar Open, and immediately showed his class as he won 23 of 26 first-serve points.
The top four seeds all had first-round byes, and all won their opening matches in the second round.
Second seed Jo-Wilfried Tsonga was untroubled as he beat Philipp Kohlschreiber 6-3, 6-4 but it was a different story for the third and fourth seeds, John Isner and South African Kevin Anderson.
Isner took the first set in a tie-break against fellow American Sam Querrey, and then dropped the before fighting back to take the match 7-6 (10/8), 6-7 (4/7), 6-4.
Anderson was also tested in tie-breaks before overcoming Robin Haase of the Netherlands 7-6 (10/8), 7-6 (7/5).
"It was a really tough match," said Anderson.
"It was a little windy. It was tough to find your rhythm. But I just stuck with it. It's my first match. Given that, I thought I played pretty well."
Anderson, ranked 12th in the world, won the first set on a Haase double fault and was down 1-4 in the second-set tie-break before winning six of the next seven points.
Roberto Bautista Agust reached the last eight with a 6-4, 7-6 (7/3) win over American Donald Young, while Fabio Fognini took just 47 minutes to beat Thiemo de Bakker 6-1, 6-1.