Winger Njabulo Manqana scored four minutes into injury time when he converted a clever pass by Kagiso Senamela in Durban on Wednesday night.
“The mentality of the players to pull off such a win was great. It's an incredible result for us,” Rosslee said.
The victory at Moses Mabhida Stadium came just as the game appeared destined for a draw after a frustrating evening for both teams in front of goal.
Manqana had the final say with his strike keeping AmaZulu in 13th place in the Absa Premiership standings, but with the relegation gap now widening.
“We knew tactically that we were coming up against a very strong team, hence the reason why they are sitting third on the log,” Rosslee said.
“They're very difficult to break down and they are well organised and structured."
A long way to go
Rosslee, however, admitted they still had a long way to go to reach their full potential, with his team now set for a three-week break due to their exit from the Nedbank Cup.
“We're nowhere near where we want to be. We're only at 60% to be honest with you," he said.
“We need to improve on a host of things and this upcoming three-week break will give us a fantastic opportunity to iron all the creases out.”
Stars' boss Cavin Johnson was disappointed with the result, questioning some of the performances by his players after they fell eight points behind log leaders Kaizer Chiefs.
“I thought we should have won the game,” Johnson said.
“We hit the post twice in the first half and they didn't threaten us, but they scored the goal in injury time that mattered. But that's football.
''With respect to my players, a lot of them were a little bit off today."
Wits 2-1 win
Meanwhile, Wits were not celebrating, despite their 2-1 win over Maritzburg United on Wednesday night, according to the Students' assistant coach, Andre Arendse.
The Clever Boys fought back from a goal down in the league encounter, played in front of a lively crowd led by a brass band at Bidvest Stadium.
“It was definitely not our best performance and the three points are the only thing we are happy about," Arendse said.
"If you look at the game overall and the chances that we created, I think we should have came out with a better result, at least 5-1."
Wits climbed to sixth place in the Absa Premiership standings, though they remained well off the pace in the race for the title, while Maritzburg dropped to seventh position in the table.
While Arendse was not entirely satisfied, the former Bafana Bafana goalkeeper, who serves as assistant to Clive Barker, was pleased his players made a smooth tactical transition from their last match which was a 1-1 draw against table toppers Kaizer Chiefs at the weekend.
'Credit must go to the boys'
“The game plan had to change a little for us from that of the Chiefs game last week, where we had to be a lot more defensive because we were away from home," he said.
"In this game we had to be more attacking, and even though we started slowly, credit must go to the boys. They fought hard to make sure we won this one."
Arendse believed Ryan Chapman's 87th minute thunderbolt strike would be in the running for the goal of the season.
"It was a great strike and don't think any keeper would have got close to saving that one.
"More important was the timing of the goal. With the clock winding down it allowed us, as the coaches, to make substitutions and protect the lead." – Sapa