The 34-year old LA Galaxy striker has scored 65 international goals for Ireland in 136 appearances following his hat-trick in Saturday's 7-0 Euro2016 qualifying win over Gibraltar.
When assessing the scoring tally of the former Tottenham ace, ex-Manchester United midfielder Keane indicated that it comes as no shock that his old national teammate has produced what he has during his fabled career.
"Robbie is a goalscorer, the stats will tell you that," he said. "There's no surprises with Robbie.
"To be fair to him, he keeps doing it. He keeps doing the business and trains well, he's a good professional. I'm not surprised by that at all.
"We know what Robbie brings to the team.
"We know the hardest part of football is scoring goals and Robbie has done that for what, the last 12, 15 years for Ireland, so there were no surprises there with Robbie."
Keane's 18-minute treble on Saturday was the fastest hat-trick ever in European Championship qualifying and takes him to 21 in UEFA campaigns, beating the previous record of 20 set by Turkey's Hakan Sukur.
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