Onyango, who has been Sundowns' number one choice for years, said Goss' inclusion to the team will add value to the goalkeeping department that boasts of the experience of Kennedy Mweene, Riyaad Pieterse together with Jody February and youngster Abram Ngcobo.
READ: Mosimane makes bold Langerman claim after Nedbank Cup victory
However, he says the former Wits goalie will have to fight to take the number one jersey from him.
"Goss coming into the team is a good signing, looking at his quality. He has done well for Wits and I believe he is one of the goalkeepers who has done fantastic work for them (Wits) when we were in the bubble, he conceded few goals. He is welcome at Sundowns. He is a young man with a lot of energy and he has got a bright future ahead of him," said Onyango.
"We have to support each other when he comes through. He has to fight to get into the team because it is a different environment for him. We were also once new in the club and we had people who helped us to stabilise and try and play for the club. It is a new challenge for him and there is a little bit of a difference between Sundowns and Wits.
"He has to work hard and get the team to the next level because that is the most important thing, it is not an individual thing. I believe he has the ability to do that and learn two or three things from us and we are still also learning from him as we are getting old because learning never stops," Onyango added.
He continued: "There's Jody February coming through, there's Abram from the development team and there is still Reyaad. It is going to be competitive but very good competition with the 'keepers and we hope everyone will give his best."
For more news your way, download The Citizen's app for iOS and Android.