Chelsea are considering whether to lodge a final bid worth £40m for the Everton defender John Stones after seeing their third offer of the summer for the England international flatly rejected by the Merseyside club.

Everton made it clear, yet again, on Tuesday that they are not interested in parting with the 21-year-old defender, who has been capped four times, and will not enter into negotiations with the champions. That resolve could yet be tested by an offer which would establish Stones as the most expensive defender in English football, though raising the bid to £40m would effectively see Chelsea doubling their original valuation of the centre-back.

The London club’s opening offer was worth £20m, with subsequent bids of £26m and, on Monday, £30m having been rejected. Roberto Martínez has refused to deny claims the player is attracted to the possibility of moving to Stamford Bridge, where he would compete in the Champions League this season, although the defender – who has four years remaining on his Everton contract – has not agitated for a move. Indeed, his form for and commitment to Martínez’s side to date this term has been exemplary.

José Mourinho, who has made no secret of his frustration at Chelsea’s lack of progress in the transfer market this summer, believes Stones would represent both a long-term asset and a player who could go straight into his first-team, particularly with two of his current senior defenders struggling.

Both Branislav Ivanovic and John Terry have endured difficult starts to the campaign, Chelsea’s worst since 1998, with the captain substituted at half-time on Sunday as the title winners succumbed 3-0 to Manchester City, last season’s runners-up.

Terry, who had never been hauled off in 177 Premier League games for Mourinho, is expected to start at West Bromwich Albion on Sunday though the manager will consider removing Ivanovic from the firing line. The Serbia defender had suffered a torrid afternoon against Swansea City’s Jefferson Montero on the opening day, and was just as error-prone at the Etihad Stadium.

The Ghana left-back Baba Rahman, a £21.7m signing from FC Augsburg over the weekend, trained with his team-mates at Cobham on Tuesday and could potentially come into the side, with César Azpilicueta switching flanks to his more natural right-back berth at Ivanovic’s expense. Thibaut Courtois, who was suspended at City, should return in goal despite having suffered a minor knee injury in the warm-up to the Swansea game.

Mourinho also hopes to have Victor Moses back in training this week and possibly in contention at The Hawthorns after a slight groin injury. The Nigeria international, who has spent time on loan at Liverpool and Stoke in recent campaigns, was one of the more impressive performers on the pre-season trip to the United States.