The new head coach has helped guide England to three successive victories that have partially erased the disappointment of the World Cup campaign, which resulted in a quarterfinal elimination at the hands of Portugal.

But sustaining the feel-good factor and consolidating England's position at the head of the qualifying group depends largely on their performances against their Balkan opponents over the week.

Nothing less than a repeat of last month's victory against Macedonia in Skopje will keep the critics quiet, but the acid test for McClaren is likely to come in Zagreb when Slaven Bilic's Croatia defend an unbeaten record in home qualifying games stretching back over 15 years.

A major bonus for McClaren, however, is the return from suspension of Manchester United striker Wayne Rooney for the two games.

The 20-year-old was forced to sit out the qualifiers against Andorra and Macedonia last month due to the red card received in that fateful World Cup defeat against the Portuguese, but he is now back in the fold and McClaren admits that the 30-million-pound forward will be one of the first names on his team-sheet.

McClaren said: "I couldn't wait for Wayne to join up and have the opportunity to work with him for 10 days. He will be an asset for us, but he just needs games at the moment -- everybody can see that. But Wayne Rooney, believe me, will be in the team as long as he's fit.

"Players have to be playing well and have to be in form but Wayne is a world-class player and can make the difference at any given moment. He's in my team."

Rooney's recent goalscoring record for England is surprisingly poor -- the striker has not found the back of the net in a competitive fixture since the 4-2 win against Croatia in Euro 2004 -- yet his record of 11 goals in 33 appearances highlights his obvious threat.

And with McClaren toying with the idea of moving him further forward to play in a role just off Peter Crouch in a 3-5-2 formation this weekend, the former Middlesbrough manager believes that it is simply a case of fine-tuning to get the best out of Rooney.

McClaren said: "We need to get Wayne into positions where he can score more goals and create more and get better service into the final third.

"You have to give him the freedom to go and play, to go and express himself, but you do that with all the players within the structure of the team.

"I think he's most effective where he is at the moment, behind the striker, linking the play. Being effective in the final third is one of the important things and it's about how often we can get him into that final third, too."

McClaren must decide who will replace the injured Owen Hargreaves in the holding role at the weekend.

Manchester United midfielder Michael Carrick is the favourite to stand in for the Bayern Munich man, who is currently sidelined with a broken leg.