Portsmouth’s poor form continued as John Mousinho’s league leaders made it one win in six games by slipping to a shock 3-0 defeat at home to Leyton Orient.

A disastrous opening half saw stuttering Pompey conceded all three goals before the break.

Orient could have been ahead inside the first 10 seconds, but Dan Agyei’s shot was deflected for a corner.

They did take the lead after 30 minutes when a one-two between Shaq Forde and Max Sanders saw Forde score easily.

It was 2-0 five minutes later when Jordan Brown stabbed home after a goalmouth scramble.

Pompey had a chance to get back in the game after 40 minutes with a penalty after a foul on Jack Sparkes, but Colby Bishop’s tame effort was easily saved.

Things got worse for Pompey in the last minute of first-half added time when Agyei headed home from a corner.

Orient maintained their dominance in the second half, stifling Pompey’s efforts to get back into the game and came away worthy winners.

Leyton Orient gained bragging rights in their London derby with near-neighbours Charlton thanks to a goal from Omar Beckles.

The central defender met a cross on 80 minutes from substitute Dan Agyei – who had only been the field for two minutes when he sent a ball into the box – to earn a 1-0 win.

Neither side had anything to show for their intense energy in the first half with a lack of true quality proving their shortcoming.

Orient keeper Sol Brynn kept his side on level terms before the break when he was at full-stretch to keep out efforts from Corey Blackett-Taylor and Chem Campbell, after Watford loan striker Shaq Forde had spurned a good opportunity in the third minute for the home side when he blazed over the bar following a Theo Archibald corner.

Orient improved after the interval and were rewarded with Beckles’ defining goal, although they were indebted to Brynn’s fine late save from Blackett-Taylor that protected their win.

The victory exacted revenge for the O’s defeat by the same scoreline in the opening match of the season at The Valley.