The all-Mancunian semi-final was heading for extra time until Rooney popped up to nod home his 21st goal of the season to secure a 3-1 win and complete a 4-3 aggregate triumph.
It might not have been as individual a triumph as his four-goal salvo against Hull on Saturday but for Ferguson, Rooney's performance was even better.
"It was much better than Saturday," Ferguson said of his number one striker, who played up front on his own.
"I know he scored four goals on Saturday but his control leading the line and his link-up play was fantastic. Overall it was a wonderful performance - world class."