Antonio Conte spent £57million on deadline day to acquire the pair, with the return of Luiz among the most surprising moves of the transfer window. Chelsea had spent the entire summer searching for a new centre-back only to return to a player Jose Mourinho was only too eager to cash in on in 2014.
Alonso is another returning to the Premier League, though he perhaps made less of an impact at Bolton and Sunderland. The former Fiorentina wide man replaces Abdul Baba Rahman in the Chelsea squad after Schalke took the full-back on loan.
He will wear the No.3 shirt but Luiz was unable to take his former No.4, which was handed to Cesc Fabregas in the same summer that the Brazilian was sold the Paris Saint Germain for £50m.