Lisandro Martínez has apologised for claiming that Jason Wilcox, Manchester United’s director of football, failed to strengthen sufficiently in the summer window after discussions with the manager, Michael Carrick, and executive on Thursday.

While any disciplinary action taken against him will not be made public by the club, it is thought Martínez has been fined.

The defender’s apology came on Thursday evening after the 28-year-old failed to offer one when issuing an initial statement on Wednesday regarding his outburst that came after Tuesday’s 2-0 Champions League loss at Atlético Madrid.

He posted on Instagram: “Today I met with the club’s leadership and the manager. It was a very positive conversation, where we were able to exchange views and speak openly about what happened after Tuesday’s game.

“Everyone knows that I am a passionate person and that I live football with great intensity. The frustration of the defeat led me to express how I felt at a time and place that perhaps were not the right ones, and for that I want to apologise.”

The apology is a considerable climbdown. After the Atlético defeat, Martínez was scathing of Wilcox and his recruitment in the last window.

He said: “I expect more [investment], 100%. I expect more from our technical director [Wilcox]. As players we have to do more but it is also important when you make a strong squad to be ready for this kind of night. Last season we did everything, we created the base to create an amazing team.”

Martínez claimed that Carrick had not been backed sufficiently. “I don’t think so. He does his best. You can’t keep changing, changing, changing the manager. What about other areas?” he said.

While it is understood Martínez’s apology was his decision alone, United spent £155m in the market – all on midfielders, Andrey Santos, Youri Tielemans, and Carlos Baleba, despite Wilcox targeting a left-back.

The wider squad agrees with Martínez’s stance regarding recruitment and has been left frustrated following a poor start to the season, with Carrick under considerable pressure.

A return of six points from six league games is United’s poorest since 1986 and Carrick’s side have already been eliminated from the Carabao Cup by Brighton.