The newly promoted Absa Premiership outfit looked to be heading towards an invaluable point on Saturday, but Jomo Sono's men were undone by a 89th minute goal from Amakhosi substitute Josta Dladla.
Cosmos midfielder Sono has now cited inexperience as the reason behind the team's lapse in concentration.
"We have a very young squad and for many of them it's their first time playing in the Premiership. I don't think they were nervous or anything like that, but just their lack of experience showed early on and very late in the game," Sono told the PSL's official website.
"We have to learn that we cannot allow players like that space, whether it's in the first minute or last minute. The difference in the Premiership and the NFD (National First Division) is that mistakes are punished.
"We also have to know that point is good enough when playing away and especially against a team like Chiefs. But we did not close up shop and lacked some focus late on."