Porto have re-signed former defender Pepe after the Portugal international had his contract at Turkish side Besiktas terminated.
The 35-year-old, who won Euro 2016 with Portugal, has signed a two-and-a-half year contract.
Pepe first signed for Porto in 2004 -- the summer after they won the Champions League with Jose Mourinho as manager -- and won six trophies in three seasons before joining Real Madrid in 2007.
Pepe established himself as one of Europe's top central defenders at the Bernabeu, creating a formidable partnership alongside Sergio Ramos, and winning the Champions League on three occasions before moving to Besiktas in 2017.
He failed to win a trophy in Turkey, but he helped the club progress from the group stage of the Champions League for the first time in their history as they finished first, only to lose 8-1 on aggregate against Bayern Munich in the round of 16.
He also played in six of the seven matches as Portugal won Euro 2016.
Porto are six points clear at the top of the Primeira Liga table and face Roma in the Champions League round of 16.