The 26-year-old was due to play in World Cup qualifiers against in Armenia on Saturday and Hungary next Tuesday.
However, Diogo has picked up an issue while training with his national team. The Portuguese Federation reported Diogo was suffering from "muscle discomfort", with Lazio's Nuno Tavares called up to replace him.
The defender operated at left wing-back in the 3-2 win over Burnley at the weekend, supplying an assist for Bryan Mbeumo's goal with a magnificent piece of work down the flank and clever cutback to the Cameroon international.
Team-mate Bruno Fernandes remains with the Portugal camp, as they prepare for their game in Yerevan this weekend.