Loan watch: Mensah bags first pro' goal
The 19 year-old, who recently extended his loan spell with the Essex outfit, scored after five minutes as Braintree won 2-1.
Mensah was replaced after an hour by the scorer of Braintree's winner, Dan Holman.
Former Hornet Chez Isaac was also a playing substitute.
In Spain, Iriney was sent-off as Mallorca were beaten 2-1 at home by Barcelona 'B'.
The experienced midfielder was given a straight red after 43 minutes, with the hosts' goalkeeper having been sent off after just five minutes.
Diego Fabbrini's wait for his first Siena goal continues, with the forward substituted 62 minutes into their 1-1 draw against Empoli.
In League One, Connor Smith played 55 minutes of Gillingham's 2-1 loss at strugglers Bristol City before being substituted.
Back in Spain, Javier Acuna came off the bench for Osasuna with 25 minutes of their 2-0 defeat against Levante remaining. The forward was unable to salvage anything for Osasuna.
Finally, Uche Ikpeazu was once again not involved with Crewe Alexandra as he struggles to recover from an ankle injury.