Sunderland overcame the spirited challenge of Championship strugglers Oxford United to move into the FA Cup fifth round with victory at the Kassam Stadium.

Habib Diarra's first-half penalty settled a tie the Premier League side deserved to win - but also one in which Matt Bloomfield's side emerged with credit.

Oxford, struggling one place off the bottom of the Championship, made eight changes but acquitted themselves well, particularly in the first half.

New South Korean signing Jin-Woo Jeon was lively early on while another new acquisition Jamie Donley, on loan from Tottenham Hotspur, had a powerful shot punched away by Sunderland keeper Robin Roefs.

The underdogs were furious when referee Thomas Kirk pointed to the spot after Christ Makosso challenged Dennis Cirkin after 32 minutes, Diarra completing the formalities.

Oxford keeper Matt Ingram, deputising for first choice Jamie Cumming, distinguished himself in the second half with a succession of fine saves as Sunderland applied more pressure, denying Romaine Mundle, Chemsidine Talbi and Trai Hume.

Sunderland, however, were rarely in serious danger as they took another step on the road to Wembley.

Sunderland head coach Regis Le Bris made six alterations from the team that suffered their first home loss this season, a narrow defeat to Liverpool, for what could have been a testing trip to Oxford United.

It may have taken Diarra's penalty, hotly-contested by Oxford's players and the home support, to settle the contest but there was no dispute that Sunderland, lying 11th in the Premier League were worthy winners.

The Black Cats could have added more in the second half, but for fine work by home keeper Ingram, who made the most of a rare start.

Sunderland's travelling support were rain-soaked but delighted at the final whistle when the sun finally shone on Oxford, following another satisfactory result in a fine season.

As for Oxford United, this was respite from their troubled season in the Championship, where they face a real struggle to avoid the drop, with head coach Matt Bloomfield and his team facing a desperate fight for survival.

They can take some heart from defeat here, however, as they were in the game until the final whistle despite relying on keeper Ingram to ensure the visitors did not extend their lead.

In many respects, this was a free hit for Oxford, but aspects of this performance will offer encouragement, as will the warm reception their supporters gave them at the final whistle.

Oxford United's next game is away to Championship promotion chasers Middlesbrough on Saturday, 21 February (15:00 GMT).

Sunderland face Fulham at the Stadium of Light on Sunday, 22 February (14:00 GMT).