But Brandon Mason has left Fratton Park and returned to Coventry City
Masampu was given a nine-minute runout at Luton today as the Blues picked up a 1-1 draw.
The 21-year-old, who was mistakenly identified as Mason at Kenilworth Road, was taken to Stamford Bridge in 2017 after impressing with non-league outfit Metropolitan Police.
He left the Premier League outfit two years later, and was most recently operating at non-league level with Dulwich Hamlet last November.
Masampu has spent time on trial with Sheffield Wednesday this summer and featured in a number of the Owls’ warm-up games, before Darren Moore opted against offering the left-back a deal.
Cowley has chosen not to pursue a move for Mason, after the 23-year-old linked up with Pompey this week.
The former Watford man featured in the 3-3 draw against Bristol City on Tuesday, with either a loan or permanent deal available to the Blues.
It’s not a move Cowley is looking to advance, however, with Mason returning to the Sky Blues.
The Pompey boss remains in the market for a left-back to offer competition for Lee Brown next term.
Liam Vincent was the first signing of the summer and operates in that position, but the 18-year-old arrival from Bromley is seen as one for the future.
Pompey have made eight signings this summer, with Cowley clear a host of additions are still required before the transfer window closes on August 31.