SOCCER/Chelsea (0) Barcelona (0):A WEEK of very public complaints from Barcelona's players at Chelsea's perceived overly physical style of play at the Camp Nou has prompted Didier Drogba to accuse the Catalans of putting pressure on this evening's referee, Tom Henning Ovrebo, in the hope that they receive more protection in tonight's semi-final second leg.

A string of Barca players, led by Andres Iniesta and Xavi, but echoed by the manager Pep Guardiola, had complained Chelsea escaped relatively unpunished from the first match despite allegedly littering the contest with fouls designed to suffocate the Spanish club’s attacking threat. Both sides received two bookings in that match, much to Guardiola’s stated disbelief, and Chelsea’s players are wise to the motivation behind their opponents’ complaints since.

“We were not upset or surprised,” said Drogba, who himself had become infuriated in the first match at Dani Alves’ apparent willingness to crumple to the turf at the merest hint of contact.

“They complained, sure. But their complaints are coming from frustration because they didn’t score. I can understand that, but the referee was good for this kind of game. He showed good control. They have tried to put a bit of pressure on the referee for the game at Stamford Bridge but, while we know it’s going to be a game that everyone wants to watch, we know the referee will have to be at his best.”

Ovrebo, intriguingly, sent off Juninho for two bookable offences and cautioned five more Lyon players in their 5-2 last-16 defeat at the Camp Nou and yet the local press back in Barcelona still poured scorn on his performance as having done them few favours. Indeed, there were times yesterday when it felt as if the animosity that had flared in last week’s game had pursued both sides back to Stamford Bridge.

Guus Hiddink left his pre-match media conference to whistles from some of the Catalan press – they were, in fact, directed at club officials rather than the manager himself – though the mind games had already taken an intriguing twist. Where Barcelona arrived still smarting from their inability to pierce the Londoners’ defence in the first leg and braced for a more adventurous Chelsea in the return, they were confronted with a charm offensive from their hosts’ temporary manager.

Barca, said Hiddink, were “respected worldwide”. “Their strategy and philosophy, how they’ve built their club, this style of playing whoever their manager is, educating their players and signing their players, that’s all good to see,” he said.

“Other clubs can take that as an example. If you have that philosophy, you can stay at the top in your league and also in Europe. We can respect and admire that, even as an opponent.”

Yet behind the flattery there is a steely resolve. The goalless draw secured last week represented a fine achievement but it has left Chelsea caught between a desire to pour forward in search of the tie’s potentially critical goals and the threat that Barca, a side who have scored 146 goals in all competitions this season, are just as potent an attacking force away as they are at home.

Real Madrid, crushed 6-2 in the Bernabeu, discovered as much at the weekend and Thierry Henry, struggling with a knee injury, is expected to come through a fitness test this morning to play.

Yet there must be more ambition to the Blues this time around, and certainly a greater command of possession, frittered away too easily at the Camp Nou. Barca arrive without Carles Puyol and Rafael Marquez, and with the left-back Eric Abidal probably being asked to play in an unfamiliar role at centre-half.

The last time the Frenchman played in that position in a high-profile game he was sent off 10 minutes into his country’s defeat to Italy at Euro 2008, conceding a penalty as France departed the tournament with a whimper.

Barcelona’s weak underbelly must be exploited. “I watched their game at Real on Saturday and, as a lover of football and the way football can be played, I enjoyed it very much,” said Hiddink. “The slightest error will be punished, so we have to play very intelligently against them. But you must not play without any emotion. If you do, it might put the brakes on your own performance. If you can combine both, you have a very good game.

“Last week, in Barcelona, we did very well tactically but there were some periods when I would have liked us to take more of the initiative. We needed to show a little bit more when we had the ball. All their comments made afterwards were born of frustration. It’s only human that, if you are used to scoring every week and then you don’t, you get frustrated when the emotion is still raw. We have the right to compete ourselves, and we must again.”