Chelsea travel to the Estadio do Dragao on Tuesday night to take on Portuguese giants FC Porto in a bid to claim their second win of the Champions League campaign.
The night holds importance not just for Chelsea's campaign, but also because their destination is a place where Jose Mourinho first made a name for himself, lifting the Champions League trophy as Porto manager in the 2003/04 season.
Much has changed at Porto since Mourinho left, though, and whilst they might not be as formidable a force as they once were, the Blues must expect to enter this game and be given a good fight and rid of their own fragilities in the process.
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Here are three changes that Mourinho and Chelsea must make against Porto:
1. Reorganise their defence
Prior to their game against Newcastle United at St James' Park last Saturday, Chelsea seemed to have regained some of their defensive solidarity.
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They conceded only once in three games - against Walsall in the Capital One Cup - and the general consensus was that the leakage in their defence was plugged.
Kurt Zouma and Gary Cahill coped well with the defensive high line and Branislav Ivanovic seemed to be recapturing his form of last season, whilst the out-of-favour John Terry was also solid when called upon.
But on Saturday, though, the Blues' defence looked disjointed once again, with two defensive errors costing Chelsea dearly twice.
Perhaps the problem was a lack of real leadership on the pitch, or perhaps it was just pure naivety on the west Londoner's part, but come Tuesday, Mourinho must sort his defence out in such a way that will combat the aerial threat of Porto striker Vincent Aboubakar and the tricks of winger Miguel Lanyu.
2. Chelsea's players need to run more
Against the Magpies, Chelsea's players were too slow in closing down players, therefore allowing their opponents more time and space.
In the first half, Mourinho's men seemed somewhat lethargic, and whilst they drastically improved in the second half, laziness is something that cannot afford to happen against Porto - the Blues' midfield, in particular, must increase their intensity.
3. Bring changes to the team
Changes are of a necessity for Mourinho, with those still underperforming needed to be dropped.
Ivanovic, despite an upturn in form, should be dropped and Cesar Azpilicueta take his place whilst Baba Rahman slots in at left-back. John Terry should start alongside Cahill or Zouma in order to provide leadership and combat the aerial threat of Aboubakar.
Ramires, Willian, and John Obi Mikel all deserve to start given their impressive displays last time out, with the former two both scoring at the weekend.
By giving his fringe players playing time and dropping the underperforming regulars, Mourinho will create intense competition that can only mean for an overall improvement across the team, both against Porto and in the long run.