Manchester United players are baffled by Louis van Gaal's substitutions as the Dutch manager continues to struggle to influence games through his changes.
Van Gaal introduced Ashley Young for Marcus Rashford at half-time in the weekend defeat at Tottenham in a move that was widely derided by United supporters.
The impressive Timothy Fosu-Mensah had to come off injured for Matteo Darmian in the second-half and Van Gaal also withdrew the ineffectual Juan Mata for Memphis in the second-half.
A source told M.E.N. Sport: "Players haven't got a clue what the f**k his substitutions are all about."
Van Gaal has made 33 half-time substitutions during his time in charge of United - 25 were tactical and eight were enforced by injury. United have won 13, drawn six and lost 11 of those games.
In recent weeks, the United manager has had a tendency to make tactical substitutions involving full-backs. Darmian replaced Marcos Rojo in the win over Watford, Fosu-Mensah replaced Darmian at West Brom, Darmian came on for Guillermo Varela in the FA Cup draw with West Ham, Antonio Valencia and Darmian replaced Varela and Rojo against Liverpool, Valencia and Fosu-Mensah came on for Rojo and Darmian at City, while Fosu-Mensah replaced Rojo at the pause against Everton.
Van Gaal's substitution struggles have worsened this season, having watched Marouane Fellaini, Adnan Januzaj and Ashley Young emerge to influence games in his first United campaign.
His in-game management has drawn regular criticism from United supporters who were impressed by Van Gaal's impact at the 2014 World Cup.
As Netherlands manager, Van Gaal memorably replaced Jasper Cillessen with Tim Krul prior to the quarter-final penalty shootout against Costa Rica. Krul saved two penalties as the Oranje recorded a rare shootout triumph.
However, in the semi-finals, Van Gaal's decision to start Nigel De Jong against Argentina proved costly. He substituted defender Bruno Martins Indi before De Jong, fit again after limping off nine minutes into the last 16 tie with Mexico, departed on the hour mark.
With penalties looming, Van Gaal sent on Klaas-Jan Huntelaar for Robin van Persie, scuppering his initial plans to send on specialist Krul, and Cillessen conceded four spotkicks as Argentina won 4-2.
In United's FA Cup quarter-final defeat to Arsenal last season, Van Gaal made two half-time substitutions which contributed to their elimination. He replaced the injured Luke Shaw, having risked him despite not being fully fit, and made a tactical change by bringing Ander Herrera off for Michael Carrick as 10-man United lost 2-1.