[4][5][6] Supplier: adidas[citation needed] / Sponsor: Samsung[7] Midfielder and all-time top scorer Frank Lampard left the Blues after 13 trophy-laden years, having played 648 games and scoring 211 goals.

David Luiz's transfer was completed just a day after the signing of Fàbregas and the Brazilian left the Blues having played 143 games and scoring 12 goals.

[20] Chelsea also announced that they agreed a fee with Atlético Madrid for Striker Diego Costa, thought to be in the region of £32 million,[21] and eventually signed him on 15 July.

[25][26] The same day, a youthful Chelsea team comfortably defeated League 2 side Wycombe Wanderers 5–0 in their first pre-season friendly at Adams Park in Buckinghamshire.

Also that day, another very youthful Chelsea team narrowly defeated another League 2 side Wimbledon in their second pre-season friendly at Kingsmeadow in southwest London, winning the match 3–2 after being two goals down at half-time; the comeback was aided by a few senior players brought on for the second-half.

This match marked the first competitive action for new signings Costa, Fàbregas and Thibaut Courtois, who started in goal after a three-year loan spell at Atlético Madrid.

After the international break, Diego Costa was named Player of the Month for August after scoring four goals in three games and sending Chelsea to the top of the table.

Fàbregas grabbed his first Chelsea goal but it was cancelled out by Klaas-Jan Huntelaar, who scored with 28 minutes left to secure a point for Schalke.

In a close fought-encounter, Pablo Zabaleta was sent off after 66 minutes, giving Chelsea the advantage and allowing Schürrle to givethe Blues the lead.

In Chelsea's next match, they knocked Bolton Wanderers out of the League Cup third round after winning 2–1 thanks to a debut goal from defender Zouma and a strike from Oscar.

A first half penalty by Eden Hazard and the ninth goal of the season for Diego Costa sent the Blues five points clear at the top of the table ahead of the international break.

Drogba's powerful header gave the Blues the lead, but a last minute equaliser from Robin van Persie meant the sides shared the points.

Emre Can gave the Reds the lead before goals from Gary Cahill and Diego Costa sent the Blues seven points clear before the international break.

[62] A dominating performance against West Bromwich Albion sent kept Chelsea seven points clear at the top of the table, thanks to goals from Costa and Hazard.

Despite Chelsea failing to score for the first time in the season, they went six points clear of defending champions Manchester City at November's end.

[67] The Blues fell behind to two Papiss Cissé goals and Drogba pulled one back, but Mourinho's side failed to secure the equaliser as Manchester City closed the gap at the top to three points.

[72] In the League Cup Quarter Finals Chelsea progressed by beating Derby County 3–1 at the iPro Stadium,[73] where they faced 2012 winners Liverpool.

[74] A superb victory against Stoke City meant the Blues were on top at Christmas, goals from captain John Terry and Cesc Fàbregas gave José Mourinho a win against adversary Mark Hughes.

[75] Terry scored for the second successive game as the Blues continued their form and defeated West Ham United 2–0 at Stamford Bridge.

[84] Despite a superb first-half performance from Newcastle United and in particular Rémy Cabella, the Blues ran out 2–0 winners after goals from Oscar and Diego Costa.

[85] José Mourinho recorded his biggest Premier League away win as Chelsea manager as the Blues hammered Swansea City 5–0, thanks to two doubles from Costa, Oscar and a goal from Schürrle.

[86] A week later, Chelsea threw away a two-goal lead and lost to League One side Bradford City in the FA Cup fourth round.

[89] Striker Costa was banned for a stamp on Liverpool midfielder Emre Can, missing games against Manchester City, Aston Villa and Everton.

[93][94] Additionally, left back Ryan Bertrand made the permanent move to Southampton for £10 million after having spent the first half of the season on loan at the club.

Costa went off with an injury after 75 minutes and his replacement Rémy scored moments later to send Chelsea six points clear with a game in hand.

A first half penalty kick from Hazard sent Chelsea on their way before Charlie Adam scored from 65 yards to equalise, yet for the second game, Rémy netted a second-half winner.

[117] A week later, Chelsea battled to a 0–1 win at QPR, Fàbregas scoring with the Blues' only shot on target in the 88th minute to send them seven points clear of second-place Arsenal.

Despite Manchester United having 70 per cent of the ball's possession, they rarely troubled Courtois' goal and the Blues held resolute to record a 13th win in 16 games at Stamford Bridge.

The young Blues won the FA Youth Cup for a second consecutive season thanks to goals from Tammy Abraham, Dominic Solanke and Isaiah Brown over two legs.

Despite conceding first, goals from Drogba, Terry and Ramires sent Chelsea 13 points clear at the top of the table, guaranteeing them a spot in 2015–16 UEFA Champions League group stage.