Here are six who could make the biggest impact in this season's English Premier League.
IMAGES from the UEFA Champions League matches played on Tuesday
Ten-man Arsenal suffered a 3-0 Premier League defeat at Leicester City on Sunday in another blow to their hopes of finishing in the top four and qualifying for the Champions League.
Images from the Champions League football matches played on Wednesday night.
Sergio Aguero proved he is still vital to Manchester City's cause as the Argentine paved the way for a routine 2-0 victory at bottom club Sunderland on Sunday.
News of that transpired on and off the football field
This and more from the happenings in the world of football
Bayern Munich may be missing some of their biggest names when they travel to Porto for the first leg of their Champions League last eight on Wednesday but the Germans are confident they have enough firepower to defend their favourites tag.
Barcelona's rescheduled La Liga game at home to Real Madrid is set to take place on December 18 as both clubs came to an agreement after the match, due to be played on October 26, was postponed amid violent political demonstrations in Catalonia.
Manchester City's Premier League title celebrations were put on hold as rivals Manchester United produced a remarkable comeback from two goals down to win their derby clash 3-2 at the Etihad Stadium on Saturday.
Manchester City continued their imperious stranglehold over the League Cup with a 2-1 victory over Aston Villa with goals from Sergio Aguero and Rodri in the final at Wembley on Sunday to win the trophy for a third straight season. City became the first side to win the competition three seasons in a row since Liverpool claimed four straight titles from 1981 to 1984.
A summary of Sunday's action in Serie A and La Liga.
Manchester City tightened their stranglehold at the top of the Premier League on Wednesday by trouncing bottom club West Bromwich Albion 3-0 as nearest rivals Manchester United suffered a chastening 2-0 defeat at Tottenham Hotspur.
Players from both teams took a knee in solidarity with the Black Lives Matter movement before Wednesday's game at Toyota Stadium in Frisco, Texas, but their gesture was overshadowed by booing from a small section of fans.
Manchester City stumbled to the most unexpected defeat of the Premier League season on Saturday before neighbours Manchester United began their brave new world under Ole Gunnar Solskjaer with a glorious reminder of long-forgotten attacking swagger.
Barcelona take a 4-0 advantage to Munich but are wary of Bayern's wounded pride when they face the Germans on Tuesday in their Champions League quarter-final return leg. Barca coach Pep Guardiola warned their high scoring victory in Spain last week could bring the best out of the German champions, who have called the defeat a debacle and said they have no real chance of qualifying.
Bayern Munich midfielder Thiago Alcantara will be out of action until early November after having surgery on Monday for damaged ligaments, the club said.
Images from Sunday night's English Premier League matches.
Samuel Eto'o scored twice to help Barcelona rally from two down to draw 2-2 at Real Betis on Saturday, stretching their Primera Liga lead to 13 points.
Barca made a slow start to the campaign under their new coach but after beating Paris Saint Germain in the quarter-finals they are on course to repeat the treble success.
Tottenham Hotspur reached the semi-finals of the Champions League on away goals after a 4-3 (aggregate 4-4) defeat to Manchester City in a breathtaking quarter-final second leg game on Wednesday.
IMAGES from the English Premier League matches played on Tuesday
The 41-year-old has made 640 appearances in Serie A, within striking distance of the 647-game record of AC Milan defender Paolo Maldini. Buffon began his career at Parma before moving to the Turin club in 2001.
Manchester City captain Vincent Kompany has suffered another setback after sustaining a groin injury in the League Cup win at Swansea City, the Premier League club said on Friday. After suffering a thigh injury in City's 1-0 Champions League semi-final defeat by Real Madrid in May, Kompany returned to action at the Liberty Stadium on Wednesday but was forced off before the end. "City skipper Vincent Kompany is receiving treatment for a groin injury sustained in Wednesday's EFL Cup win over Swansea," the club said in a statement on their website
Yet even without a transfer fee, Messi's colossal salary, reported to be the highest in world football, means very few clubs would be able to afford him.
Reigning champions Manchester City took the lead after 24 seconds but suffered a shock 2-1 defeat at Newcastle United.
Whatever happens, there will be no shortage of drama between now and May 12.
Thierry Henry said he will consider leaving Barcelona during the winter transfer window if coach Pep Guardiola leaves him on the bench too often.
Ronaldinho, Deco and Samuel Eto'o do not feature in Pep Guardiola's plans at Barcelona.
Images from Saturday's action in the Premier League.
Images from the UEFA Champions League matches played on Tuesday.
IMAGES from Saturday's English Premier League matches.
Pep Guardiola got off to a winning start as Barcelona coach with a comfortable 4-0 home victory over Wisla Krakow in their Champions League third qualifying round first leg on Wednesday.
Manuel Pellegrini has said he would choose winning the Premier League with Manchester City and being shown the door over continuing as the team's manager for an extended period without any major success.
ManchesterCity's season began to unravel when Kevin de Bruyne missed 10 matches with a knee injury but as he showed when he scored against Paris St Germain on Tuesday, anything is possible with him back in the team.
Former Manchester United manager Alex Ferguson will reportedly be consulted over the appointment of the successor of the sacked David Moyes at the Old Trafford club.
In the 69th minute, the Argentine slid in to meet a cross from Sterling and, although it appeared Mings got the final touch for an own goal -- ultimately, a decision for the dubious goals committee -- no-one was going to persuade Aguero that he was not responsible for putting City two up.
Manchester United remain very dangerous opponents despite their struggles domestically as they focus their efforts on Europe, Bayern Munich coach Pep Guardiola said on the eve of their Champions League quarter-final first leg.
Images from the English Premier League matches played across England on Sunday.
Manchester City have signed Chile goalkeeper Claudio Bravo from Barcelona on a four-year contract for an initial 18 million euros (15.37 million pounds), the clubs confirmed on Thursday.