Robin van Persie  is out of Manchester United 's Capital One Cup  clash with Liverpool  on Wednesday due to injury.The striker picked up a groin problem prior to the 4-1 defeat to Manchester City on Sunday and did not feature at the Etihad Stadium.David Moyes has confirmed the Dutchman will not be involved at Old Trafford, but has an "outside chance" of featuring against West Brom in the Premier League on September 28.Speaking at press conference ahead of the Liverpool match, Moyes said: "I don't think Robin will play on Wednesday. But I think he'll have an outside chance for Saturday.”Moyes also believes it is time to move on from their convincing derby day weekend defeat and believes he will learn more about his players character in the coming weeks.He continued: "It's gone now. I can't do anything about it so we move on and get ready for the next game.“I'm still getting to know all the players. I'll get to know a few more this week and see what they can do."Finally he talked up the rivalry between Manchester United and Liverpool and hinted he will include a number of established players for the Capital One Cup clash, in a match which could mark Luis Suarez's return to competitive action for Merseyside outfit.He added: “It's a big rivalry and it could take on a bigger significance than people might expect."I think it means that Liverpool have a got a really good player. Does it change the complexion? I don't know. I'm not looking at Liverpool too much except that I know the quality of Luis Suarez is very good."The cup has been a route to giving young players an opportunity, but obviously this is a really big tie."Manchester United currently sit in eighth spot in the Premier League, having taken seven points from their opening five league matches.