It has been a struggle, but Manchester United's defence of the European Cup has at least been carried through to the tournament's second phase. This was an evening which could have gone so badly wrong for Alex Ferguson and his team. Defeat here may have signalled the end of the fight even before the gloves had come off. But, as Ferguson is fond of reminding his team's detractors, champions can be expected to play like champions when it matters most.

With the resurgent Austrians of Sturm Graz providing the final first-phase opposition at Old Trafford next Tuesday, United will now probably win their group, a feat which appeared to be beyond them after their meek surrender in Marseille last week.

At the end of a game which began lethargically and then slowed down, Croatia Zagreb had been comfortably subdued, the evening's only surprise being that United's final margin of victory was not more generous. No mind, the primary objective of passage through into the last 16 where the elite will be unencumbered by the make-weights has been achieved.

There was a bonus, too. Predictable bookings for David Beckham and Paul Scholes means they both now face one-game suspensions, bans which will be served in next week's dead rubber.

"This was a decent performance and I am simply relieved that we are through to the next stage and that everything does not depend on our last game," said Ferguson. "It wasn't a great performance, but I felt that we were quite comfortable in the second half. They are a difficult team to play against and this is a difficult place to come to."

Zagreb do possess several players of high pedigree, notably Daniel Saric, but they are too often undone by over-ambition and almost childlike predictability.

They seized the early initiative last night, cleverly ring-fencing possession and building patiently, a process aided by United's frustrating inability to deliver even the simplest of passes without recourse to a fortuitous ricochet. Zagreb's early pressure was almost rewarded in the fifth minute when Saric cut inside Denis Irwin to steer in a rising drive which Mark Bosnich, perhaps wisely, opted to push aside rather than attempt to collect.

United had contributed little but their first strike on goal after 32 minutes was to go in. It was not quite a gift, but it was close, Saric upending Scholes 25 yards from goal. It was Beckham territory and he did not disappoint, firing a low free-kick just inside the far post for his first goal of the season.

United were in control of proceedings and they were to underline what was a growing superiority just four minutes into the second half. Irwin's cross from the left was only partially cleared and Roy Keane's right foot did the rest, although his shot did take a deflection off a Croatian boot.

Not until stoppage time did Zagreb successfully puncture a defence which had been superbly marshalled by Jaap Stam. Although the substitute Robert Prosinecki clipped home smartly from 10 yards, it was a hollow gesture at the end of a bitterly disappointing evening for Ossie Ardiles's side.

However, Ardiles had few complaints and praised United's qualities. The former Tottenham playmaker said: "United were the better team. Last season they won the title with fine away form, and that is what we saw tonight."

Ardiles was asked afterwards if he was going to resign, and replied: "No, and that is a stupid question. Will they fire me tomorrow? Anything can happen here."

Ardiles has done well domestically, for Zagreb lead their championship, unbeaten and unbowed, after 11 games. It is on the European stage they have disappointed, spectacularly so last week when they succumbed in Austria to Sturm Graz.

Croatia Zagreb: Butina, Tokic, Sedloski, Juric (Prosinecki 35), Mujcin, Rukavina, Mikic (Simic 55), Saric, Cvitanovic (Mumlek 69), Tomas, Sokota. Subs Not Used: Vasilj, Krznar, Pavlovic, Kozniku. Booked: Sokota. Goals: Prosinecki 90.

Man Utd: Bosnich, Irwin, Stam, Berg, Neville, Beckham, Keane, Scholes (Greening 68), Giggs, Cole (Cruyff 78), Yorke (Solskjaer 59). Subs Not Used: Van Der Gouw, May, Clegg, Higginbottom. Booked: Neville, Scholes, Beckham. Goals: Beckham 32, Keane 49.

Referee: D Jol (Holland).