The duo could replace Ghana pair of Mumuni Abubakar and Emmanuel Baffour who are to be offloaded by the club anytime soon.
Though Sundowns have Sumaila and Mathias on trial at the club the reality is that The Brazilians can only register foreign players next season as they have already exhausted their foreign quota of five players for this season in Alje Schut, Abubakar, Baffour, Nyasha Mushekwi and Method Mwanjali.
Even if a club decides to offload foreign players during the season the Premier League will not permit new registrations to be made during the course of the season if they have already exhausted their foreign quota like Sundowns.
Abubakar and Baffour have so far proven to be flop signings with both yet to make any contribution at the club since their arrival in July.
However, Sundowns who are keen on reinforcements at the back have brought in Sumaila and Mathias for a close look in by Pitso Mosimane.
Sumaila currently plays for Asante Kotoko where he is on loan from Ebusua Dwarfs and has already been capped at Under-20 and 23 levels for Ghana.
The 20 year-old was part of the Black Stars provisional squad for the Afcon finals but was dropped when the squad was trimmed down to 23 players but he remains highly-rated in the Ghana Premier League.
Mathias (26) is a Togolese right-back born in Nigeria but is now a naturalised Togolese.
Mathias was part of the Togo squad at the 2006 Afcon finals in Egypt and currently plays for Nigerian club Heartland but has previously played for clubs in Tunisia and Israeli.
Meanwhile, Ugandan goalkeeper Dennis Onyango is recovering well from the fever that prevented him from travelling with the rest of his teammates for the week-long tour of Zimbabwe.
Onyango pulled out of Sundowns training camp in Polokwane due to the fever and is now back home in Johannesburg recovering.