IF the restless Toon Army were unsure of the root cause for Newcastle United's malaise, Sir Bobby Robson's post-match comments acted as a perfect appraisal.

Never one to give a one-word answer when a 1,000-word reply will suffice, Robson could have been accused with labouring a point on Saturday night - when he confessed he was facing his biggest challenge since rescuing the club from relegation in 1999-2000.

As he assessed Newcastle's lame display during their third home defeat in a week - their first such run since January 1998 - Robson trotted out the same comment, mantra-like, seven times.

"We couldn't get behind Birmingham," was the gist of what Robson said time and again.

And he was right. Kenny Cunningham and Matthew Upson were superb at the heart of the Birmingham defence, erecting an impassable barrier.

But they were never turned; they seldom, if ever, had to face their own goal throughout the 90 minutes.

Thoughts, then, were of an absent friend - and to a man restricted to a role as a radio commentator on Saturday.

Craig Bellamy has his detractors, notably the Newcastle legend Malcolm Macdonald, and the irascible Wales striker must improve his goals to games ratio and curb his hair-trigger temperament.

But if ever one needed to see just how important Bellamy and his electric pace is to this Newcastle team, Saturday's game was the perfect example.

Shola Ameobi is a brave workhorse, but he has resembled a carthorse for much of the three home defeats that have been played out in front of a disbelieving St James' Park public.

Alan Shearer, who can credit Bellamy with helping to resurrect his career over the last two years, is a much less fearsome proposition without his first-choice strike partner.

Robson vowed to stick with 21-year-old Ameobi, but he knows the sooner Bellamy returns to full fitness, the more potent Newcastle will be.

Robson said: "We have to get in behind defenders and we haven't done that in the last three games.

"Craig Bellamy would help, of course. The only ways to get behind people are with clever play down the flanks or with pace up front, and we're missing Bellamy.

"Birmingham sat deep like the Partizan Belgrade defenders did. They said, 'You can have the ball in front of us but you can't get behind us.'

"On crosses, they dealt with us. We had a lot of set plays but they kept heading the ball out."

Shearer, in a refreshingly frank assessment of Newcastle's efforts, concurred with his manager that Bellamy might have made a decisive difference.

"Craig Bellamy is a big player for us. We can't use his absence as an excuse and say it's just down to that, but we've not been stretching teams," he said.

"Teams are coming to St James' Park, and they're sitting deep and allowing us space. But we have to work around that.

"A lot of teams know now that that's the way to play here - to sit deep - and we have to make sure we can get behind them and break them down.

"In the last week, we haven't created chances. Well done to Birmingham: they snuffed us out. They were on the edge of their box and made it very difficult for us."

Nobby Solano was the only Newcastle midfielder that might have, as the old football saying goes, left the pitch with white paint on his boots.

He was an outlet for his team on the right flank, but Hugo Viana played far too narrow, hinting at his penchant for a central midfield role.

When Solano was withdrawn, the decision was roundly booed by the Newcastle fans. Robson claimed later that the Peru winger was tired, but he had been their brightest attacking talent.

Laurent Robert and Lee Bowyer did little to suggest that they might engineer an equaliser, and while Robson is not facing a crisis he knows the problems are mounting.

He said: "This is the biggest challenge since my first season here.

"It won't just come right; it's not an electric light switch that you can switch on and off. But I'm confident the lads will get us out of trouble. They're the ones that can.

"I don't feel under pressure. If I came in on Monday and looked under pressure, and that filtered through the club, that would be the last thing the club needed at this stage."

Gary Speed marred a good performance at left-back with a rash lunge on Damien Johnson to concede a 59th-minute penalty.

David Dunn had his weak spot-kick saved by Shay Given, but the Birmingham midfielder lashed the rebound past the prostrate goalkeeper and into the net.

Newcastle never looked like equalising; Bowyer had a shot stopped by Maik Taylor, but Birmingham's well-drilled back four were rarely ruffled.

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