The Owls are understood to have offered 35-year-old Mariappa a contract but the offer expired at 5pm yesterday. Although there was no official confirmation, as the deadline passed it was thought the former Watford and Crystal Palace defender was heading to the A-League.
Wednesday, though, completed a deal for 29-year-old Mendez-Laing, who was loaned to Sheffield United 10 years ago and has trained at Middlewood Road for the last few weeks. He played in a friendly there last week.
The winger was sacked by Cardiff City after taking cocaine the night before a match in July 2020.
But former Bluebirds manager Neil Warnock took him to the Riverside in February and he made two starts and seven substitute appearances for Boro, scoring once, before his short-term contract ended. Since then he has been without a club. Jack Hunt and Lee Gregory returned from injury at Accrington Stanley on Saturday, where Josh Windass was an unused substitute, and Massimo Luongo made his third start of the season. They were still without the injured Dominic Iorfa, Sam Hutchinson, Marvin Johnson and Lewis Gibson. Fisayo Dele-Bisharu is expected to be fit after going off injured.
Last six games: Sheffield Wednesday WLDWDW; Milton Keynes Dons WDWDWL
Referee: R Madley (Huddersfield)
Last time: Sheffield Wednesday 0 Milton Keynes Dons 0, April 19, 2016, Championship