"I was so made up for Robbie because he was in a position he doesn't usual play in," said the former Liverpool striker. "He normally likes to play off Fernando Torres in the same way as he played behind Dimitar Berbatov at Spurs.
"But at the Emirates he was asked to play the lone striker role and I thought he was fantastic. He worked so hard for the team and will take a lot of confidence from that goal."
Rush also had a few words for Mark Lawrenson, after the pundit claimed that Steven Gerrard had told him that Keane was leaving Liverpool.
"It was also a great reaction after the comments made by Mark Lawrenson last week about Keane's future," added Rush. "To come out and say what he did about Keane moving on in January was absolutely stupid. It didn't help the club or player."