Pierre-Emerick Aubameyang joined Arsenal from Borussia Dortmund for a club-record fee of around £56 million on Wednesday, with Olivier Giroud moving to Chelsea as part of a complicated transfer jigsaw.

As the clock ticked down to the closure of the transfer window in England at 2300 GMT, Tottenham announced the signing of Lucas Moura from Paris Saint-Germain but Manchester City pulled out of a move to sign Leicester's Riyad Mahrez.

Top Premier League clubs have splashed the cash in the January transfer window, desperate to qualify for the top four, which guarantees entry into the lucrative Champions League.

Aubameyang, 28, signed a contract with the Gunners until 2021, becoming Arsenal's second big-name signing of the January transfer window after Henrikh Mkhitaryan joined from Manchester United.

The signing, which translates as $79 million, or 64 million euros, will boost Arsene Wenger's forward options after the departure of Alexis Sanchez to United in a swap deal with Mkhitaryan but raises questions about Alexandre Lacazette's future in the starting line-up.

The prolific Aubameyang compared himself to club legend Thierry Henry, telling Arsenal Player he was attracted by the "big history" of the club, who lost ground in the Premier League with a 3-1 defeat to Swansea on Tuesday.

The Gabon international will be reunited at the Emirates Stadium with former Dortmund team-mate Mkhitaryan -- a tweet on Arsenal's Twitter account pictured the two players together with the message "Friends reunited".

Aubameyang posted a message on Instagram apologising for the circumstances surrounding his departure from Germany but describing himself as "crazy".

"Perhaps it was not the best way for me to have decided, but everyone knows that Auba is crazy," Aubameyang said.

"And yes, I am crazy lad, hahahaha. I have made mistakes, but I never had any bad intentions. I will never forget these four-and-a-half years at Borussia Dortmund."

Chelsea later announced the arrival of Arsenal striker Giroud on an 18-month contract for around £18 million and Michy Batshuayi's departure for Borussia Dortmund in a loan deal until the end of the season.

Frenchman Giroud, 31, who has struggled to hold down a regular starting spot since joining Arsenal in 2012, said he was delighted to be joining their London rivals.

Belgian forward Batshuayi, 24, arrives in Dortmund as a direct replacement for Aubameyang, to complete the three-way puzzle.

Brazil winger Lucas challenged his new Spurs team-mates to win the Champions League after arriving from PSG for a reported £25 million.

"It's a chapter in my life, a new challenge for me. I am so happy," Lucas, desperate for first-team action, said in a video posted on Tottenham's Twitter feed.

Pep Guardiola's City were reported to have pulled out of a bid for Mahrez, who won the Premier League with Leicester in 2015-16, after making a final cash-plus-player offer worth up to £65 million, according to Sky Sports.

City have lost influential Germany winger Leroy Sane for at least six weeks with an ankle injury and with the club competing on four fronts Guardiola suggested he may need reinforcements.

"Right now, it's the same as (Alexis) Sanchez, it's not the place to talk about it. It's so difficult," Guardiola said on Tuesday when asked about Mahrez.

"If things are not possible, then nothing is going to happen. We don't have too much and we play every three days. We have to find solutions."

City paid a club-record record fee of £57 million for young French centre-back Aymeric Laporte from Athletic Bilbao, whose deal was confirmed on Tuesday.

Swansea, whose win against Arsenal on Tuesday saw them move out of the Premier League's bottom three, brought Ghanaian forward Andre Ayew back to Wales from West Ham late Wednesday -- 18 months after he joined the Hammers for £20.5 million.

The Swans said they had re-signed the 28-year-old for a club record but undisclosed fee on a three-and-a-half year contract.

The London Evening Standard estimated bringing Ayew back to the Liberty Stadium would cost Swansea between £18-20 million.

Earlier in the transfer window, Jurgen Klopp's Liverpool signed Virgil van Dijk from Southampton for £75 million -- a world record for a defender.

German World Cup winner Mesut Ozil gave Arsenal a big boost by finally agreeing a new contract that will see him become the highest paid player in the club's history, according to the BBC, which said he would earn around £350,000 a week.

There was no official confirmation from Arsenal but Ozil posted a tweet with a picture of him signing photos with the message: "Had a busy day signing things."

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