Kieran Richardson's superb first-half double breathed new life back into Sunderland's Premier League relegation fight and dented Pompey's extraordinary away league record this season.

Redknapp could be forgiven for having second thoughts about his career choice after watching the way his side capitulated against hosts supposedly reeling after last week's dismal FA Cup defeat to Wigan.

Richardson swept home the opener in the 32nd minute, after Kenwyne Jones' persistence pushed him past Sol Campbell to retrieve an apparently lost cause from the by-line.

The former Manchester United man doubled his tally one minute from the break with a cool finish from the edge of the box and almost grabbed a deserved hat-trick when he rattled the bar early in the second half.

Pompey's best chance was a golden opportunity spurned by leading scorer Benjani Mwaruwari in the ninth minute, when the Zimbabwean scooped the ball wide from close range to sum up Redknapp's dismal day.

His opposite number Roy Keane could hardly have wished for a better response from his side just a week after admitting he was "ashamed" of his players' performance in their 3-0 loss to the Latics.

From the first minute, his players hustled and harried their opponents and fully merited a victory which will give them renewed belief that such spirit and commitment could lead them to safety.

Danny Collins, Anthony Stokes and Dean Whitehead all had chances in the first 10 minutes as the visitors sat deep - before Benjani ought to have done better in his side's first foray forward.

Pompey's best spell of the game continued, with Niko Kranjcar forcing a fine reaction save out of Craig Gordon in the 17th minute, but the home side soon resumed control and seldom looked like slipping up.

Stokes headed over the bar, and Daryl Murphy shot just wide of James' left-hand post before Jones helped to create Richardson's opener.

Returning from a knee injury, the big striker barged past Campbell - who appeared to have given the ball up as dead - before clawing it back from the by-line into the path of his team-mate to sweep home.

It got even better for Richardson one minute before the break when he beat Hermann Hreidarsson to Murphy's ball on the edge of the Pompey box, before firing confidently past James.

Sunderland looked anything but content with their excellent first-half work, and Richardson came close to grabbing his and the Black Cats' third three minutes after the re-start.

Stokes knocked Jones' right-wing cross back into the former Manchester United man's path, but Richardson's rising shot from just outside the box sailed inches over James' bar.

Pompey responded well, Pedro Mendes having a long-range effort blocked by Nyron Nosworthy before play swung to the other end where James had to get down well to hold a Murphy cross.

The frantic action continued when Benjani burst past Nosworthy only to hit a poor shot which was booted clear by Jonny Evans - with Gordon beaten.

In the 59th minute, Richardson again came agonisingly close to his hat-trick when he let fly with a rising left-foot shot from the edge of the box which clattered the bar.

Sunderland continued to hold the ascendancy, while Redknapp made changes to little effect - and the dangerous Benjani was superbly shackled by Nosworthy and Evans in the home defence.

The home side ultimately coasted home to the obvious delight and relief of Keane.

Benjani's early profligacy might not have been the only missed opportunity Redknapp is left to rue.