Pedro is ready to make an immediate impression for Chelsea after joining the Barclays Premier League champions from Barcelona.

The Blues, bidding to recover from their worst start to a season in 17 years, signed the 28-year-old Spain forward on a four-year deal on Thursday.

Pedro, who cost £21.4million ($33.8m), with £2.1m ($3.3m) of the payment comprised of performance-related add-ons, trained immediately with his new team-mates and could make his debut against West Brom on Sunday.

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"I am ready to start playing straight away if the manager selects me," Pedro said on chelseafc.com.

"I am in very good shape because I have already played for Barcelona this season.

"It's a new challenge and I can't wait to get going."

Pedro's arrival is a significant boost to the Blues, who lost the Community Shield to Arsenal, drew with Swansea and were beaten 3-0 by Manchester City.

The City loss came at the end of a week marred by Jose Mourinho's decision to remove first-team doctor Eva Carneiro and head physiotherapist Jon Fearn from the bench, one which attracted criticism of the Portuguese.

Mourinho was a major reason for Pedro choosing Chelsea ahead of Manchester United, whose long-term interest in the forward ended as the Blues made their move.

Cesc Fabregas, who swapped Barca for Chelsea in 2014, was another factor as Pedro bids to add to his extensive trophy haul with his new club.

Pedro added: "He (Mourinho) is one of the main reasons why I'm here. He phoned me a few times and said he needed me to make the team stronger.

"He has won titles wherever he has been. I am really looking forward to playing under him and hopefully winning more titles.

"I spoke to Cesc. We are very good friends. I knew I would feel at home here and that was one of the main reasons why I decided to join."

Left-back Baba Rahman, a £21m ($33m) arrival from Augsburg, could also make his debut at the Hawthorns, while Pedro's arrival could have repercussions for Juan Cuadrado, disappointing since his January arrival from Fiorentina, or Victor Moses, who is back at Chelsea after spending last season on loan at Stoke.

Oscar and Willian are others who could find themselves in need of justifying their places, although Mourinho will be less inclined to lose the Brazilian pair.

The Blues also hope to conclude the signing of Everton defender John Stones before the transfer window shuts on September 1, although the Toffees are standing firm and determined to hold on to the England international.