Chelsea have signed Michael Hector from Reading, where the defender will remain for the season as one of the Premier League champions' 32 loan players.
Hector joined Nantes defender Papy Djilobodji in signing for Chelsea on transfer deadline day.
Senegal international Djilobodji will remain with the first-team squad, but the 23-year-old Hector will continue playing at the Madejski Stadium.
"Chelsea Football Club have today completed the signing of Michael Hector from Reading," Chelsea said on their official website.
"The 23-year-old centre-back, who has signed a five-year-contract, will return to Reading and spend the remainder of this season on loan at the Madejski Stadium."
Republic of Ireland midfielder Stephen Quinn has agreed a move to Reading.
The 29-year-old, a free agent after leaving relegated Hull at the end of last season, will sign a three-year contract with the option of a fourth.
Royals boss Steve Clarke told the club's website:
"Stephen is an unassuming player but has always caught my eye and, when I knew he was available, I targeted him quite early in the summer.
"His performances are always of a good standard and he is a talented, industrious, aggressive midfielder who can be influential in games.
Quinn joined Hull from Sheffield United in 2012 and made 97 appearances - including the FA Cup final defeat by Arsenal last year - and scored five goals.
Aston Villa and Reading have been charged in relation to crowd disturbances occurring after their FA Cup quarter-final matches, the Football Association has announced.
It is alleged that Villa and Reading failed to prevent spectators encroaching on the pitch following the clubs' sixth-round victories against West Brom and Bradford respectively.
Both clubs have until Thursday to respond to the charge.
Ayegbeni Yakubu is hoping to fire Reading to Wembley after the Nigerian striker return to English football to fulfill his dream.
The striker was absent when former club Everton lost to Chelsea in the 2009 FA Cup final due to injury, something Yakubu wants to make amends for.
Former Everton striker Ayegbeni Yakubu showed his finishing prowess as Reading progressed to the last eight of the FA Cup at the expense of a Derby County side reduced to 10 men for 50 minutes.
Derby looked the better side until their full-back Stephen Warnock was sent off for a second yellow card in the 39th minute.
Hal Robson-Kanu's goal was cancelled out by Darren Bent but Yakubu, signed as a free agent during the January transfer window, netted the winner.