Ferguson is asked to explain tirade

London: The FA will await an explanation from Alex Ferguson for his verbal tirade at an assistant referee after Manchester United's game against Tottenham Hotspur before deciding whether to charge the manager with misconduct.

Ferguson branded Simon Beck's performance at White Hart Lane on Sunday as "shocking" and appeared to question whether the official was biased against the Premier League leaders by claiming that the club had "history with him".

The United manager was furious that Beck failed to flag for a challenge on Wayne Rooney by Steven Caulker, the Spurs defender, that he felt should have resulted in a "clear penalty" in the second half before Clint Dempsey cancelled out Robin van Persie's header to secure a 1-1 draw in stoppage time. The result cut United's lead at the top to five points.

The FA has given the Scot, who did not travel with his squad to Qatar for a short training camp because he is attending a charity event, until Thursday to respond to its approach.

Although Dempsey's late strike was a bitter blow to United in their quest to reclaim the title, Ferguson could at least take some comfort in the sight of Van Persie scoring his 11th goal in his past 11 matches and 22nd for the club since his �24 million move from Arsenal last summer.

Van Persie is the leading contender to win the two main Player of the Year awards for the second season running, but as an insight into the Dutchman's mentality, he played down his impact at United so far by claiming that he should have done better.

"Not really well," Van Persie said when asked how well he thought he had done this term. "It is going well but if you start to believe it's going well, you're going down. When I look at those last 10 games, it's a good step but to me it should have been 10 games and 14 or 15 goals. At least four or five [chances] I shouldn't have missed."

Van Persie added that was enjoying playing with team-mates who made him feel "that I'm surrounded by champions". He said: "I'm seeing things again that I didn't see for a long time [at Arsenal]. When I first came to Arsenal years ago, I saw things from [Dennis] Bergkamp and Thierry Henry I'd never seen in my life before. Now I'm seeing those things again and that makes me really happy. It's like a kid in a sweetshop."

Meanwhile, Ferguson is monitoring Victor Valdes's situation at Barcelona as the Manchester United manager weighs up a move for a new goalkeeper.

United ' who were on the verge of finalising a deal to sign Wilfried Zaha, the England forward, from Crystal Palace Monday ' have been scouting potential replacements for David De Gea for about two months amid growing concerns about the Spain Under-23 goalkeeper's suitability to the Premier League.

De Gea's susceptibility to high balls was exposed again on Sunday when a weak punch at a cross allowed Dempsey to earn Tottenham Hotspur a 1-1 draw in stoppage time at White Hart Lane as United's lead at the top over Manchester City was cut to five points.

United are thought to have discussed the possibility of bringing in a goalkeeper this month but the matter is unlikely to be addressed until the summer.

The news last week that Valdes does not intend to sign a new contract at the Nou Camp has alerted United to the possibility of signing the 31-year-old, who would be reasonably priced given that the Spaniard has only 18 months remaining on his deal. A move for Valdes could raise the possibility of a swap deal involving De Gea, 22, whom United signed from Atletico Madrid for �18.3million in June 2011.