Portsmouth came from behind to beat 10-man Cambridge 3-1 in a dramatic game at the Abbey Stadium.Robbie Simpson netted a highly contentious opener for the hosts in the fifth minute, running on to Luke Berry's pass and slotting past Aaron McCarey. The linesman had flagged for offside but took it down after Simpson had scored and the goal was allowed to stand.U's captain Mark Roberts was sent off after the half-time whistle for pushing goalkeeper McCarey during an altercation. Pompey assistant manager Leam Richardson was also dismissed for his part in the melee.Portsmouth turned the game around with two goals in a matter of moments. First, Gareth Evans' fine cross from the right forced a sliced own goal from Leon Legge in the 67th minute before Matt Tubbs turned home Gary Roberts' ball across goal two minutes later.Tubbs then sealed the result three minutes from time with a simple header after Kal Naismith hit the bar.Deep into injury time Evans was sent off for a nasty challenge on Elliot Omozusi.