Oxford United secured their status as a Championship side for another season as they handed Sunderland a fourth consecutive league defeat.

Gary Rowett's U's opened the scoring in the first half through defender Ben Nelson's header and early in the second, Michal Helik poked the ball home from close range to make it two.

Oxford were promoted to the second tier last season for the first time in 25 years following a 2-0 win over Bolton in the League One play-off final.

They started the season with Des Buckingham in charge but after parting company with him in December, former Millwall boss Rowett came in and eventually got them over the line in this campaign.

Sunderland know their hopes of winning promotion will rely on a successful play-off campaign as they have made certain of a fourth-placed finish.

Some fans may worry, though, as they have failed to win any of their last five games.

Oxford now have a four-point buffer to 22nd-placed Hull City and with each team having just one more regular league game this season, they are safely out of reach.

Cameron Brannagan looked to start the game in a similar fashion to the way he snatched the U's a point against Cardiff on Monday when he unleashed a dangerous effort from 25 yards but was denied by Sunderland keeper Anthony Patterson, who dived and palmed it away one-handed.

The U's continued to impose themselves on Sunderland early on, offering plenty to encourage the home fans as the Black Cats struggled to get into their groove.

Oxford took the lead through Nelson just before the half-hour mark when he rose highest to meet a ball floated into the area, and headed it in at the near post.

It was his first goal of the season and first for Oxford since joining the U's on loan from Leicester in the summer.

Rowett's side also started the second half well, and doubled their lead three minutes into the second period.

Patterson denied Brannagan from a free-kick but the onrushing Helik and was there to stretch and direct the ball home with his right foot.

With 20 minutes remaining, Sunderland threatened to get back in the game with an audacious overhead effort by Enzo Le Fée sailing inches wide but they will now look for a lift at home to QPR next Saturday.

Gary Rowett told BBC Radio Oxford:

"It's absolutely incredible - the focus was there from the players.

"I'm really proud of everyone at the club and I thought we played really well.

"I thought we created some good moments in the game because we were playing a good team.

"I need a lay down and a glass of wine but that will probably have to wait until tomorrow night."

Sunderland boss Regis Le Bris speaking to BBC Radio Newcastle

"The result, game and performance is disappointing.

"We didn't match their energy and they (Oxford) play a style of football that is difficult to manage.

"They deserved their win, we are not happy about the dynamic of the team and the way we are playing right now.

"We have to find solutions on the pitch and we didn't manage to do it, I expected more."