Gareth Ainsworth's late winner condemned Division One leaders Portsmouth to only their second league defeat in 19 games.

Ainsworth sidefooted the ball home with just four minutes remaining after the ball had dropped kindly to him after good work from Nigel Reo-Coker.

Wimbledon substitute Patrick Agyemang struck just eight minutes after going on to level matters after Paul Merson's excellent goal put the visitors ahead in the first half.

Merson's spectacular strike, his 10th of the season, lit up a disappointing opening period but Wimbledon battled back to claim the points.

Neither side created any opportunities in the opening 15 minutes with the hosts working hard in midfield and Lionel Morgan keeping a close eye on Pompey playmaker Merson.

The visitors forced a corner after 18 minutes but it was the only attacking threat they had shown as they struggled to deal with a bumpy playing surface.

Stuart Murdoch's side, playing a more direct style and benefiting from a strong wind behind them, looked more likely to open the scoring and Alex Tapp forced Shaka Hislop into a good left-handed save following a corner after 23 minutes.

But Pompey went ahead against the run of play two minutes later through Merson.

Kelvin Davis made a fine stop to deny Svetoslav Todorov but when the ball came loose, Nigel Quashie rolled the ball into Merson's path and he hammered it into the top corner from 22 yards.

Morgan fired a left-foot shot wide as Wimbledon sought an immediate response before the injured Jason Crowe was replaced by Gary O'Neil for the visitors.

Tim Sherwood was booked for a foul on Morgan just after the interval before Hislop comfortably gathered Wayne Gray's long-range effort after 55 minutes.

Gray was soon replaced by Agyemang and the 22-year-old levelled matters after 65 minutes with a sweet finish after Neil Shipperley's flick-on.

Davis made an excellent save to keep out Quashie's left-foot shot from distance before former West Ham goalkeeper Hislop made a smart save at Agyemang's feet.

Vincent Pericard came on for Todorov with 10 minutes remaining but it was Wimbledon who had the last word thanks to Ainsworth's late strike.

Teams

Wimbledon: Davis, Volz, Williams, Andersen, Hawkins, Ainsworth, Tapp, Morgan (McAnuff 62), Reo-Coker, Shipperley, Gray (Agyemang 58).

Subs Not Used: Gier, Darlington, Gore.

Goals: Agyemang 66, Ainsworth 87.

Portsmouth: Hislop, Primus, Festa, De Zeeuw, Crowe (O'Neil 33), Sherwood, Merson, Quashie, Taylor, Todorov (Pericard 80), Ayegbini.

Subs Not Used: Diabate, Tavlaridis, Kawaguchi.

Booked: Sherwood, Quashie.

Goals: Merson 26.

Att: 10,356

Ref: P Walton (Northamptonshire).