LONDON (AFP) - Sir Alex Ferguson will step up his bid to sign a new striker ahead of Manchester United's Premier League opener after refusing to rule out a move for Thierry Henry.

Ferguson has been considering a 20 million pounds (25 million euros) bid for Barcelona star Henry and the United manager must be reaching for the cheque-book after his side failed to break down Portsmouth in Sunday's Community Shield at Wembley.

After a tepid goalless draw notable mostly for United's failure to finish the few chances they created, it took a penalty shoot-out for the European champions to win the annual curtain raiser to the English season.

United's lack of cutting edge must concern Ferguson because Cristiano Ronaldo won't be back for several weeks after ankle surgery and Wayne Rooney is still recovering from the virus he contracted during the club's visit to Nigeria, while Louis Saha is struggling with injury as usual.

Ferguson has been keen to sign a forward since the end of last season but a move for Tottenham's Dimitar Berbatov - his number one target - has stalled, forcing the Scot to look elsewhere.

Enter Henry, who found it hard to adjust to life at Barca last season and could be persuaded to leave the Nou Camp for Old Trafford.

When asked about reports linking him with the former Arsenal star, Ferguson could have rubbished the story but opted for a deliberately vague response.

"There is a name every day. That is the nature of the business," Ferguson said. "I can't answer it because I've not got a direct answer.

"It's possible we could sign someone this week. We are trying. We've got one or two options we are looking at and hopefully we can get something done before the start of the season.

"It has been pressing since the end of last season. We like to operate with four strikers and we have not been able to do that."

Although Ferguson will hope his strikers are sharper by the time Newcastle arrive at Old Trafford next weekend, he has no such concerns about his defence.

Marshalled superbly by Rio Ferdinand, United never gave Portsmouth's little and large duo of Peter Crouch and Jermain Defoe a chance.

"Rio is now the best centre-half in the world by far," Ferguson said. "That was an exemplary performance. He did not give one foul away and intercepted every ball that came towards him.

"He broke out of defence in comfort so many times it was unbelievable. He is a magnificent player.

"He is 30 now and because he has experience his potential is now being fulfilled in a big way."

With Rooney and Ronaldo out of action it was left to Carlos Tevez to carry United's attack. But at times the Argentine was too fired up and found himself accused of stamping on Portsmouth defender Hermann Hreidarsson.

Hreidarsson, who was grabbed round the throat by Tevez after the clash, said: "I was down and he stamped on me. I thought he could have avoided me, there was no need for it. That was why I reacted and why I grabbed his leg."

After a shocking miss in the first half Darren Fletcher hit the bar with a sublime chip and David James denied Tevez twice before the match went to penalties.

Lassana Diarra blasted Portmouth's first spot-kick over the bar, then Edwin van der Sar saved Arnold Mvuemba's effort with his legs and Glen Johnson shot wide to ensure United got off to a winning start.

Harry Redknapp's FA Cup winners barely registered as an attacking force and assistant Joe Jordan admitted they are still looking for more signings to follow the imminent capture of Tottenham defender Younes Kaboul.

"We came here with just 18 players and we know we are going to need a bigger squad because of the extra demands on the UEFA Cup which is new ground for us," Jordan said.

"It is going to take a lot for players to play Saturday-Thursday-Sunday but we have to be competitive.

"Kaboul should help. He's a been a long-term target of the manager. He's only 22 and is coming to a good place to learn, with Sol Campbell and Sylvain Distin."