Everton boss David Moyes has expressed his concern that the heavy international schedule many of his players are facing in June could disrupt his pre-season preparations.

Yakubu, Joseph Yobo and Victor Anichebe have already played one World Cup qualifier for Nigeria this month and could all feature in another three during the next fortnight.

Steven Pienaar faces a similar workload playing in the same group for South Africa as, even though they are the hosts for the 2010 tournament, they are competing because the games double up as African Cup of Nations qualifiers.

And in the American zone, the USA's double header with Barbados will keep goalkeeper Tim Howard in competitive action until June 22.

This extended round of games all but wipes out the valuable rest time between the end of the international calendar and the return to pre-season at the beginning of July.

But the considerable risk of squad members picking up injuries while on international duty is also worrying the Everton manager.

"It's really disappointing that these players have to play so much," Moyes told the Liverpool Daily Post.

"We've got five players away on international duty, and these World Cup qualifiers mean they are having a summer of football.

"I think Tim Howard will be involved in three friendlies and a couple of qualifiers so they really don't get the rest they should.