The Tottenham forward netted twice as Republic of Ireland defeated Macedonia 2-0 in Euro2012 qualifying on Friday night to take his international tally to 51 goals.
The brace put him past England legend Sir Bobby Charlton's total of 49 to make him the most prolific scorer in Britain's history and O'Shea did not let it pass without a few choice words.
"He's been an amazing striker for Ireland," O'Shea told Sky Sports News.
"He going to set a target that I don't think anyone will ever reach and he's got plenty more years left in him yet."
And after the win, O'Shea said that RoI's chances of qualifying for the Euros had been completely strengthened.
"With the break in between the next two games, if we had lost or drawn last night it would have been a huge dampener," he added.
"Now we have a couple of months to enjoy this result and look forward to the next two games - Slovakia at home and Russia away.
"That'll tell us whether we have a chance of winning the group and qualifying automatically.
"If we can beat Slovakia at home we'll go to Russia with a lot of confidence and then you never know."