Ronan O'Gara reveals brilliant comeback Dan Carter sent him after birthday message

21 October 2017; Dan Carter of Racing 92, left, and Racing 92 defence coach Ronan O'Gara prior to the European Rugby Champions Cup Pool 4 Round 2 match between Munster and Racing 92 at Thomond Park in Limerick. Photo by Brendan Moran/Sportsfile

Ronan O'Gara and Dan Carter are two of the all-time great out-halves - but the former All Black couldn't resist having a dig at his former coach after getting a birthday message from the Ireland legend.

O'Gara coached Carter for two and a half seasons at Racing 92, with the duo striking up a firm friendship. The legendary All Black even helped O'Gara get his current job, giving the former Ireland ten a glowing reference to the Crusaders in Super Rugby.

O'Gara moved to Christchurch last month to begin life with the New Zealand kingpins, but took the time to send Carter a birthday message as the double World Cup-winner turned 36 today.

After the Munster great remarked on how there are four years between himself and Carter, the world record points scorer in test rugby used the moment as a way to remind O'Gara of another area of separation between them.