Defending champion Rory McIlroy needed a play-off before beating Kevin Na by one hole to reach the knockout stage of the WGC-Dell Match Play in Texas. McIlroy, 26, took the lead for the first time at the 15th only for American Na to draw level at the next.

The pair could not be separated until Na, 32, found rough with his drive at the second extra hole and made bogey.

World number two Jason Day progressed too after his opponent, Paul Casey of England, withdrew with stomach pains.

Former Ryder Cup player Casey – who could not qualify from his group – won the first two holes of their match on Friday in Austin, and was two holes up until losing the fifth and sixth with bogeys, before withdrawing.

The quick victory was a welcome one for the Australian, who struggled with back spasms during his opening match on Wednesday against Northern Ireland’s Graeme McDowell.

US PGA champion Day will now face American Brandt Snedeker while McIlroy will play reigning Open champion Zach Johnson, who saw off Shane Lowry of Ireland 4&3.

Jordan Spieth eased past Justin Thomas to maintain his perfect record in the group and he will tackle former Open champion Louis Oosthuizen of South Africa.