Jose Mourinho's power-base at Chelsea was weakened yesterday as Frank Arnesen was handed responsibility for all forms of player recruitment at the club. The two men have a discordant relationship and the manager's position has been perceptibly undermined now that the former Denmark international is effectively acting as technical director.

Arnesen was tempted away from Tottenham by Chelsea chief executive Peter Kenyon 11 months ago with a view to a youth-recruitment remit, but his portfolio of duties was yesterday officially expanded as the chief scout, Gwyn Williams, left the club after 26 years' service in a variety of backroom roles.

The rise of Arnesen's star will put more pressure on Mourinho to deliver the Champions League in return for what has been almost £100 million of investment in players' transfer and wage costs this summer.

The arrivals of the world-renowned Michael Ballack and Andriy Shevchenko mark a shift in transfer policy during this transfer window, with an emphasis on highly marketable players as Arnesen seeks to manufacture the team of glitterati Roman Abramovich craves.

Though Ashley Cole is understood still to be the favoured option at left-back, Roberto Carlos is a superannuated Real Madrid galactico who has been strongly linked with Chelsea.

So far this summer, Mourinho's fingerprints can be seen only on the transfers of Salomon Kalou and John Obi Mikel.

With Abramovich having been unconvinced by several of Mourinho's acquisitions, the Portuguese manager is no longer the sole authority regarding Chelsea's transfer-market activities.

In a typically timely announcement to the Portuguese press, however, Mourinho yesterday sought to restate his position at Chelsea. "It is I who makes decisions in terms of the quality and profile of a player," he said.

"But the best players in the world don't make the best teams. You have to work hard to be successful."

Mourinho is, however, keen to dissociate himself from any suggestion that it is he who determines the inflated transfer fees Chelsea pay. "I don't get involved in the business side at all - it is (Abramovich) who makes the decisions to pay X or Y," he said.

"There are clubs whose futures are affected by the investments they make, but it is different at Chelsea. It is a club that relies on just one person. It is Abramovich's money that funds it.

"I always try to ensure that I keep a balance with the things I do. The only balance I have lost at Chelsea is the amount of money we spent on some transfers, but it is Abramovich's money.

"I am a believer in having a squad of 24 players, two for each position, not of buying for the sake of buying or buying to prevent a player going to a rival club."