Idris El Mizouni, Anthony Georgiou and Adam Przybek could all win caps later today.
El Mizouni is with the Tunisia U23s, who are facing Cameroon away in the first leg of their Africa Cup of Nations qualifier. They play the Cameroonians at home in the second game on Tuesday.
The Paris-born midfielder, who qualifies for Tunisia via his father, has previously won two caps at U23 level in addition to one game for the full squad.
On-loan Spurs winger Georgiou, who has already won six full caps, is with the Cyprus squad who take on Kazakhstan in Nicosia this evening in a Euro 2020 qualifier. They subsequently play another qualifier in San Marino on Monday.
Keeper Przybek, who joined the Blues after leaving West Brom in the summer following a trial, will win his first Wales U21s cap if he plays in their European Championships qualifier against Belgium at the Racecourse Ground, Wrexham this evening.
The Welsh youngsters have another qualifier against Germany on Tuesday, also in Wrexham.