Sir Alex Ferguson has promised no more slow starts from Manchester United this season after seeing his side fall behind in five of their six league games. United face CFR Cluj in their second Champions League group gameon Tuesday evening with Ferguson admitting to "concerns" over the team's defending.

Tottenham Hotspur won 3-2 at Old Trafford after going in at half-time 2-0 ahead. "After the first half on Saturday I had plenty of concerns," Ferguson said. "But I hope it's an awareness [thing] because we faced that situation at the end of October last season, and from then on when Jonny Evans and Rio Ferdinand played together consistently we played better."

Evans agreed: "Every defender will tell you that when you have a settled partner beside you, you get a good understanding, and with a run of games your match fitness and concentration go up."

Ferdinand's chances of a recall to the national side, however, appeared to recede further after the England coach Gary Neville insisted: "Roy Hodgson has said he will not take 34 to 35 year olds, with 80-odd caps to [major tournaments] to sit in the stands."

United's second-half display against Tottenham was far sharper, with the visitors spending most of the period hanging on to their lead. "You have to be concerned losing goals the way we did," said Ferguson. "We were well off the pace of the game. I don't think we won a tackle in the first half. Fortunately you saw Manchester United in the second half, and that was probably our best performance of the season."

The Scot identified three matches in particular where United have failed to fire before the interval. "The first half against Southampton [falling behind 1-0], the first half at Liverpool [when United were poor] and the first half on Saturday – we have some work to do in that respect."

Asked if there is anything deeper to be read into the pattern, Ferguson said: "If you go back 12 years, our norm was to start the season and build up to the second half, and then we changed when Chelsea won the title two years in a row [2005 and 2006]. We changed our approach to pre-season training. I think it [the slow starts] will be the last."

Immediately after the loss to Spurs the left-back Patrice Evra said he thought the issue was a mental one. But the manager disagreed: "I haven't given it a thought, to be honest. I wouldn't say it's mental. We conceded a bad goal after two minutes and we were always on the back foot after that. Half-time is always a good chance to correct things and the second-half performance was much better."

For the Cluj game, Ferguson has left behind Michael Carrick, Paul Scholes and Ryan Giggs, his senior midfielders, all of whom are not feeling 100%, according to the manager.

"Carrick didn't report today. He's in bed with a virus. We left Paul Scholes behind but Ryan also felt rough this morning and we sent him home. Those three players are missing, two with a virus and Paul Scholes because although he didn't feel great this morning and played great on Saturday. At 38 years of age I can't expect him to play three games like that." Their absence should mean a start for Anderson and Tom Cleverley in United's 4‑2‑3-1 formation. "Anderson is a difficult one to leave out but I don't think there's been anything wrong with the form of Scholes or Carrick, which makes it difficult to involve other players when there's always a desire to play with two wide players."

Cluj have won the Romanian title three times since Arpad Paszkany, a used-car dealer, bought the Transylvanian club in 2002. Before then CFR Cluj – the full name refers to the national rail carrier – had not won a league title since 1911.

Now managed by Ioan Andone, a former Romania international, their first national title in 2008 preceded them playing Chelsea in the Champions League, drawing 0-0 at the 25,000-seat Dr Constantin Radulescu stadium before losing the return 2-0.

Of the threat Cluj pose, Ferguson said: "We saw the performance in the last group game against Braga [winning 2-0, away]. They knocked out Basel [earlier in the competition], beating them twice. We know from our own experience last season that Basel knocked us out.

"They're a team that defend quickly and get plenty of plenty of bodies behind the ball. The main strength is counter-attack, as they showed against Braga.

"Counter-attacking has become a very important part of European football. Now it's done by four or five players, not one or two like 20 years ago, and the positive nature of the counter attack has made the Champions League much better."

Regarding Mikaël Silvestre, the former United defender who is back training the club, Fergsuon said: "[He is] just training. He's going to play in India in November, I think."