Marcos Rojo may be out for less time than feared with a dislocated shoulder after the defender’s father reportedly said his son would miss only two or three games. If that was the case he could return for Manchester United’s visit to Arsenal on 22 November.

Rojo suffered the injury in the 1-0 derby defeat by Manchester City at the Etihad Stadium on Sunday. Although there was concern at the club he could be out for a minimum of six weeks, Rojo’s father told a TV station in his native Argentina, TN.com: “It is not too severe. He will miss two or three games.”

United face Crystal Palace at home on Saturday before the international break. Argentina play Croatia at Upton Park on 11 November and Portugal at Old Trafford seven days later. Rojo’s father ruled the defender out of those matches.

With the Arsenal game only four days after the meeting with Portugal, whether the 24-year-old would be available to United’s manager, Louis van Gaal, appears in the balance.

Rojo was injured in the second half of the derby after colliding with Martín Demichelis. He required oxygen before being taken off on a stretcher.

His layoff adds to the manager’s problems in defence. Rafael da Silva, the first-choice right-back, suffered a problem in training that ruled him out of the derby and Phil Jones has shin splints. Chris Smalling’s red card against City means he is suspended, though Jonny Evans has returned to training so may be able to return for Palace’s visit.

Van Gaal will again have to call on some of his young defenders, with Paddy McNair and Tyler Blackett, who have each made their debuts this season, under consideration.

Marouane Fellaini has denied he spat on Sergio Agüero during the derby after images of him caused controversy regarding whether he had done so. But on Monday the midfielder tweeted: “The press loves to invent the stories when there aren’t any. Thanks the journalist. #ferity #tospit”.

The Football Association said Fellaini will face no action over the incident. After reviewing footage its disciplinary panel concluded the Belgian had not deliberately spat at Agüero. Similarly, City’s goalkeeper Joe Hart is in the clear over allegations that he pushed the referee, Michael Oliver.

Juan Mata, who was an unused replacement in the derby defeat, has insisted United have to focus on their own performances rather than the table as it shows the team 13 points behind Chelsea.

“To be honest, right now, rather than looking at the table we have to focus on our path in order to improve and to win games,” said the midfielder. “This situation is not what we wanted but the team must stick together and keep on going. I’m sure we will do that.

“This is the fifth time this season that one of us has got a red card, so unfortunately we already know what it means to have one player less. But even though Sergio Agüero scored and we were down to 10 men, our team showed pride and almost tied the game.”