Louis van Gaal's ruthless streak came to the fore again at the weekend when he left Robin van Persie out of his squad for the game at Crystal Palace despite the striker insisting he was fit and ready to play.

Manchester United manager Van Gaal didn't include Van Persie in the 18-man squad that eventually prevailed 2-1 at Selhurst Park, saying that he had been suffering from a virus.

However, Van Persie told friends on Saturday afternoon that he was 'absolutely fine' and was disappointed not to have played.

Robin van Persie was left out of the Manchester United squad to face Crystal Palace on Saturday

Van Persie (right) said he was fit and ready to play but missed a day in training earlier in the week

It is understood that Van Persie had indeed missed a day's training earlier last week after picking up a bug that Van Gaal himself had been suffering from for a couple of days.

But the 31-year-old was fit enough to train fully on Friday. When he wasn't included, he was left bemused, according to those close to him.

Van Gaal's decision, however, simply provides more evidence of his absolute refusal to pick players if they haven't had a full week's training in the lead up to a game.

Louis van Gaal has omitted players in the past for missing a day in training leading up to the match

Van Persie (right) travelled to London with the squad by was left out of the match-day team at Selhurst Park

The United coach's policy has already left other players frustrated this season, with another striker Radamel Falcao believing that he has been fit to play on occasions when van Gaal has decided otherwise.

'Being fit and being fit enough to play for me is not the same thing,' Van Gaal said earlier this season.

The only player to be occasionally considered exempt from Van Gaal's selection practices is Wayne Rooney. As Van Gaal's captain, Rooney is an automatic pick for every Barclays Premier League game unless he is obviously injured.

Marouane Fellaini scored Manchester United's winner as they beat Crystal Palace 2-1 on Saturday

That apart, players must train regularly with the first team squad if they are to play. That is the reason big-name players such as Van Persie, Falcao, Luke Shaw, Jonny Evans and Michael Carrick have found themselves on Under 21 duty at times this season.

In terms of Van Persie, the Holland international – captain for Van Gaal at last summer's World Cup – is happy to stay at United next season, as recently revealed by Sportsmail.

The former Arsenal striker believes next season – the last under the terms of his current contract – will be more productive than this one, given that he has suffered injury over recent weeks and months.

With United returning to European competition next season, Van Persie believes there will be more opportunity to play as Van Gaal will need to use the whole depth of his squad on a more regular basis.