"I am absolutely devastated," sighed the striker. "Ask the physios, I am the worst person to be around when I'm injured, I am not good at all.
"I just love playing games and this is a kick in the teeth for me.
"The doctor said it will be five to six weeks, probably leaning more towards six, with it being a ligament problem. I am just gutted and have just got to work hard to get back as soon as I can."
It was a case of joy swiftly turning to pain for for Robbie when he stepped up from the bench with just under ten minutes to go after Boro had levelled Dimitar Berbatov's opener. He won the night before hobbling off the pitch in agony before the final whistle.
"I've never had anything like this before, but it is football for you," he reflected. "You have so many ups that when the downs come they really hit you. It was mixed emotions for me after the game, I was happy with the win for the team, but upset over the injury that forced me off.
"We're coming into a busy period and I wanted to be involved in it, it will be the first time I have missed a Christmas since I was 17 and I won't like it."
The face of Robbie Keane said it all shortly after he had been informed that he would be out of action for five to six weeks.Robbie sustained a medial ligament strain in the left knee minutes after scoring the dramatic late winner against Middlesbrough on Tuesday and a lengthy absence has been determined following scans. He was naturally downcast on Thursday when he gave his reaction to the setback.