Robson’s return to the club where he started his career turned sour when Zenden looped a winning header past Russell Hoult in the 52nd minute.

But the new Baggies boss can count himself unfortunate he did not escape with at least a point after a battling performance by his struggling side.

Robert Earnshaw had cancelled out Darren Purse’s 32nd minute own goal within four first half minutes.

With Romanian Cosmin Contra – Robson’s only team change – looking impressive Albion looked well-placed to push on in the second half.

But instead the Baggies’ push petered out until a frantic finale in which substitute Geoff Horsfield was denied by Mark Schwarzer and Kanu somehow contrived to nudge an injury-time effort over the crossbar from just a yard out.

Albion had started well with Hungarian Zoltan Gera seeing a third-minute shot blocked by Chris Riggott.

Visitors Boro were struggling to get out of first gear as they sought to get back to winning ways after their midweek Carling Cup defeat to Liverpool.

Boss Steve McClaren brought back his big guns but it was the Baggies who created most of the chances in a solid first-half display.

Gera blazed over after being set up by Andy Johnson’s neat flick-on in the box in the seventh minute.

But Stewart Downing wasted the best early chance in the ninth minute after being fed by Franck Queudrue on the left.

The unmarked Downing had a clear scoring chance from the edge of box but shot across goal and wide of Russell Hoult’s left-hand post.

Purse nearly presented Boro with a 13th-minute opener following a weak back-header which Viduka almost reached before Hoult.

Albion had a loud penalty appeal turned down in the 16th minute when Robert Earnshaw fell under Viduka’s challenge after collecting Neil Clement’s short corner.

Zenden almost caught the Albion defence off guard with a quickly taken, long-range free-kick which Hoult tipped over his bar.

Contra might have marked his full Premiership debut with the opener in the 21st minute with a powerful drive in the box which was saved well by Mark Schwarzer.

At the other end Hasselbaink failed to poke the ball home from six yards after a fine right-wing cross by Tony McMahon.

Johnson’s run to the edge of the penalty box ended with a powerful shot being blocked by Chris Rigott just before the half-hour.

Then Riccardo Scimeca’s long-range effort was parried by Schwarzer, who also dealt with Earnshaw’s follow-up before the striker was ruled offside.

Purse presented Boro with their barely-deserved lead when Hasselbaink’s deep cross deflected off the big defender past Hoult.

But Earnshaw’s encouraging form continued just four minutes later when Contra’s superb work on the right flank set up the Welshman to sweep home Albion’s equaliser from 12 yards.

Boro began the second half with more brightness and Zenden’s goal capped an encouraging spell of visitors’ pressure.

First Gera’s foul on Ray Parlour on the right of the Albion box set up a dangerous-looking free-kick which Moore headed clear.

Then Zenden pounced with a precise header into the top corner of the net past Hoult after Downing’s left-wing cross.

Kanu could have equalised within two minutes after finding space in the box but shot wide of Schwarzer’s left-hand post.

Then the Baggies wasted two dangerous-looking set-pieces to give McClaren’s men some breathing space.

Baggies substitutes Rob Hulse and Geoff Horsfield both saw late chances to equalise denied by Schwarzer.

And in the dying seconds Kanu somehow scooped the ball over the bar from point-blank range after Horsfield had got round the back of the Boro defence.