Robert Earnshaw's devastating double gave struggling West Brom manager Bryan Robson victory at his 11th attempt as the Baggies progressed to the FA Cup fourth round with a win over Preston at Deepdale.

The visitors had dominated proceedings without ever looking too impressive before the Welsh international, who earlier had a goal ruled out for offside, earned them a win with two pieces of top-class finishing.

The first was a near-post strike from a cross from substitute Jason Koumas with 14 minutes left and the former Cardiff man added a second eight minutes later, lobbing North End goalkeeper Andy Lonergan direct from a Russell Hoult clearance.

Although there was little evidence to suggest that the Baggies are about to pull clear of Premiership relegation trouble, Robson's first victory will surely bring some confidence which was clearly lacking for long periods, even in this game.

The Baggies were clearly jittery after their miserable start to the season, but in the Premiership side's first attacking move of note, Greening won a free-kick near the corner flag after fooling Chris Sedgwick and being hauled down by Graham Alexander.

North End goalkeeper Lonergan was expecting a cross but had to deal with a powerful shot on target from the former Manchester United and Middlesbrough man which the stopper fumbled behind for a corner.

From the resulting set-piece, Youl Mawene headed onto the roof of his own net with Lonergan stranded, and a further corner from Neil Clement was only partially cleared, while Robert Earnshaw just failed to get on the end of Darren Purse's cross.

The pressure continued and Greening robbed Paul McKenna in the centre circle before Earnshaw passed right to Zoltan Gera, whose low shot from the edge of the area was blocked by Lonergan.

The Baggies were still not convincing at the back with Russell Hoult giving his team-mates a scare with a poor clearance to Neil Clement before Sedgwick shot narrowly over from the edge of the area after hitting a punch from the goalkeeper on the volley.

Injured Geoff Horsfield was replaced by Rob Hulse after just 18 minutes, leaving just three players on the pitch who had found the net for West Brom this season.

But Preston were showing little evidence of the fine recent form that has taken them to three straight wins in the course of a five-match unbeaten run, with Agyemang and Joe O'Neill, who was making his first start in Preston colours after spending last season on loan at Bury, having to work with scraps.

West Brom were only ever put under pressure by their own mistakes.

A breakdown in communication between Hoult and Paul Robinson led to another North End corner which the goalkeeper fumbled and was fortunate to clear.

An unmarked Lucketti then failed to get a firm header on McKenna's deep free-kick to the far post before, in the final minute of the first half, Hulse headed wide from Martin Albrechtsen's cross from the right.

The second half started with more of an edge than the first and six minutes after the interval, West Brom finally carved out another opportunity.

Ronnie Wallwork's clever free-kick found Hulse in space in the area but Lonergan was quick to see the danger and diverted the former Crewe striker's shot wide for a corner.

Earnshaw did have the ball in the net in the 55th minute, but the Welsh international's celebrations were cut short by the linesman's flag.

North End finally crafted an opening of their own with McKenna and Dickson Etuhu combining to make space for Alexander, but the right-back was off target with an effort from 25 yards out.

Kozluk had impressed defensively but also looked good in his first chance to get forward, cutting inside Albrechtsen and then firing just over Hoult's bar with his right foot.

Hoult was quick to rush out to clear a North End through-ball with Agyemang bearing down on him, but again looked shaky when gathering Sedgwick's cross at the second attempt under pressure from O'Neill.

Kozluk was again in the thick of the action with a well-timed goalline clearance after Earnshaw's deft header had beaten Lonergan.

But in the 75th minute, Earnshaw finally made the breakthrough with a deft finish and a goal which was laid on by Wales team-mate Jason Koumas.

Eight minutes later the victory was sealed with another superb Earnshaw strike.

The former Cardiff man lofted cleverly over the on-rushing Lonergan to double the lead.

The Baggies survived a couple of late scares to put the finishing touches to a win which will give a valuable lift to Robson.

Teams

Preston Lonergan, Alexander, Kozluk, Lucketti, Mawene, Sedgwick (Mears 84), Etuhu, McKenna, Lewis, O'Neill (Jackson 67), Agyemang.

Subs Not Used: Ward, McCormack, Davis.

West Brom Hoult, Albrechtsen, Clement, Purse, Robinson, Gera, Johnson, Wallwork, Greening (Koumas 73), Earnshaw, Horsfield (Hulse 19).

Subs Not Used: Scimeca, Gaardsoe, Kuszczak.

Booked: Hulse, Albrechtsen, Koumas.

Goals: Earnshaw 76, 83.

Att: 13,005

Ref: G Laws (Tyne & Wear).