Will Keane picked up a groin injury in the second half on Monday night

Manchester United's FA Cup win over Shrewsbury came at a price as Louis van Gaal's injury woes continued on Monday night.

It wasn't all doom and gloom for the United boss as he saw his team set up a quarter-final clash with West Ham and received the news that the injury to David de Gea is not as bad as initially feared.

The Spanish goalkeeper missed a second game after suffering a knee injury in the warm-up ahead of last week's FC Midtjylland defeat, but scans were positive with Van Gaal hopeful he may be available for the second leg.

Goals from Chris Smalling, Juan Mata and Jesse Lingard ensured the visitors conquered their League One opponents to secure a last-eight spot in the FA Cup, but their burgeoning injury list clouded an otherwise positive evening.

Youngster Joe Riley made his debut for the club, replacing Cameron Borthwick-Jackson forced off at half-time after a knock, while substitute Will Keane limped off with 14 minutes left, leaving United to finish the match with 10 men having made all their changes.

The United boss also revealed that goalscorer Lingard picked up a knock, leaving the Dutchman with further selection problems ahead of their crucial Europa League second leg clash with FC Midtjylland on Thursday.

Louis van Gaal shared a joke about being sacked after Monday night's FA cup win Louis van Gaal shared a joke about being sacked after Monday night's FA cup win

Their increasingly tough battle to secure a top-four spot in the Premier League continues at the weekend with the Super Sunday clash with Arsenal at Old Trafford.

United now have seven players who can play at full-back currently sidelined, with injuries to Matteo Darmian, Phil Jones, Ashley Young, Marcos Rojo, Antonio Valencia and Luke Shaw, as well as Borthwick-Jackson.

Striker Wayne Rooney will also be on the sidelines for six weeks with a knee problem.

Van Gaal told Sky Sports News HQ: "The second half I wanted to rest Anthony Martial and Mata but unfortunately Will Keane was injured again.

"We played with 10 men and in the end with nine because Lingard was struggling so it was very heavy for the other players."

He joked that his substitutions had been "not so good".

Asked if the fresh injury concerns made it hard to pick a team for Thursday's Europa League clash with Midtjylland, Van Gaal said: "It's much easier because I don't have many choices!"

United trail 2-1 from the first leg.