Sporting have sacked head coach Joao Pereira just six weeks after appointing him to succeed Ruben Amorim.
Pereira took over as boss of the Lisbon side soon after Amorim left to become Manchester United head coach in November, but the former Sporting B team coach endured a difficult spell at the helm.
Sporting lost four of their eight games under 40-year-old Pereira, form which has resulted in them being knocked off the top of the Primeira Liga, with rivals Benfica leapfrogging them into first place.
Rui Borges has left Vitoria Guimaraes to take over from Pereira and has signed a contract until June 2026, with the deal including an option for a further one-year extension.
“The time for me is right,” said Borges, 43, whose first game will be against Benfica on Sunday.
“It’s always right. I’m very positive, I believe things happen when they have to. It’s an opportunity we’ve all worked for.”
Amorim led Sporting to last season’s league title and departed for a fresh challenge at Old Trafford after United sacked Erik ten Hag.
Borges now faces the challenge of chasing another championship and said: “I’m the leader of the Portuguese champions and I couldn’t be happier. I look at the squad and it’s the best. It’s not even time to talk about signings.”
