Chelsea has agreed terms with Paris St Germain for defender David Luiz's return to Stamford Bridge for a fee of around £34m. Luiz, 29, travelled to London for a medical as the Blues confirmed the signing of left-back Marcos Alonso from Fiorentina for a reported £23m ($30 million). Chelsea tweeted that it had reached agreement with PSG to re-sign Luiz two years after he left for Paris. Luiz joined French champions PSG on a five-year deal after appearing for Brazil at the 2014 World Cup. PSG is reported to have paid £40m for him two years ago — £6m more than Chelsea has bid to re-sign him. Luiz joined the Blues from Benfica for £21.3m in January 2011 and made 143 appearances for the club. He had three years left on the five-year contract he signed in September 2012 when he joined Ligue 1 club. Meanwhile, Alonso moves to the Premier League for the third time in his career. Alonso agreed a five-year contract with the Premier League club as Chelsea manager Antonio Conte turned to the Spaniard after missing out on several other defensive targets. The 25-year-old is Conte's fifth signing since taking charge at Stamford Bridge, following the arrivals of France midfielder N'Golo Kante, Belgium striker Michy Batshuayi and Portuguese goalkeeper Eduardo. "I'm very happy. It's a step up in my career and I think this is the perfect place for me to continue developing," Alonso told Chelsea's website. "It's time for me to win some titles. It was an easy decision for me to make when I heard the club were interested in signing me. "My family and close friends know Chelsea is the club I have dreamt about playing for so I'm really excited about the challenge and I'm looking forward to working with my new teammates." Alonso is no stranger to the Premier League having played for Bolton for three seasons. The Real Madrid youth academy graduate was in the same Wanderers defense as Gary Cahill, who is now one of his Chelsea teammates, and he also had a loan spell at Sunderland. Alonso's arrival gives Conte options at the back, with the possibility of Cesar Azpilicueta switching to right-back and Branislav Ivanovic playing in the center of defense. Mangala moves to Valencia Manchester City's 25-year-old France defender Eliaquim Mangala has moved to Valencia on a season-long loan deal, the clubs announced Wednesday. He joined City from Porto for about 32 million pounds ($42.01 million) in August 2014 but has struggled to establish himself after making 48 Premier League appearances under the club's former manager Manuel Pellegrini. Mangala, who has not featured for new coach Pep Guardiola this season, becomes the fourth player to leave the Etihad Stadium on deadline day following the departures of Wilfried Bony, Samir Nasri and England goalkeeper Joe Hart. — Agencies