Argentina, at a puddle-ridden Lansdowne Road last November, was the Munster man's last start at No 10. Back then, it looked certain that he had firmly disposed of the challenge of David Humphreys for the Irish out-half berth. Two weeks previously, O'Gara had kept his nerve impressively, scoring six penalties in testing conditions to give Ireland their first victory over Australia in 23 years. It appeared he had lived up to the early promise. But then ...
"Of course it's been frustrating, but that's part of sport," said O'Gara. "You have to take the ups with the downs. I felt I was in great form around February, I felt confident, because every game I played has been more or less consistent. Even after that, I wasn't starting for Ireland, but I was still having an impact on games when I came on, which is an important thing.
"After I missed the Six Nations, the Leicester and Toulouse games for Munster went well. They'd been the only chances I've had to impress, so as long as I keep going like that I'll be happy."
Last weekend's test against Australia was the sixth game in a row that Humphreys started over O'Gara at out-half but, for once, the Cork Constitution player understood the reason for Eddie O'Sullivan's selection.
"I was still disappointed not to be picked for the Australia game, but I knew Eddie was treating it as an end-of-season game rather then preparation for the World Cup," said O'Gara. "David Humphreys was going home after the Australia match, so it was going to be obvious that he would play that game. I had the option of going home as well but I committed myself to the three-match tour and now I have an opportunity to show what I'm capable of."
Tomorrow's challenge will be one of the most unique in world rugby. Not many teams travel to play Tonga in Nuku'alofa for various factors, but far from being worried, O'Gara is looking forward with interest to the tussle.
"I've played against Samoa before and I suppose Tonga are going to be similar. They're going to be very abrasive and strong, but apart from that, we really don't know what else to expect from them.
"The pitches are rock hard and the grass is just like straw. I enjoy playing in the heat with the dry ball, it should be conducive to handling and hopefully it would be a good game."
Tonga coach Jim Love has made two changes from the selection that drew with the New Zealand Divisional XV last weekend. The team is made up of players based in Australia, New Zealand and Japan, meaning European-based players are not back for the World Cup preparations. One player to note is centre Johnny Ngaumo, who played for two years with Harlequins alongside Keith Wood and Paul Burke.
Hooker Paul Shields and prop forward Simon Best are potential new caps listed in the replacements for the test, which kicks off tomorrow morning, 3.30am Irish time.
Meanwhile, Australia coach Eddie Jones has urged the International Rugby Board (IRB) to change the lineout rule allowing hookers to lift the jumper. Jones reckons the rule gives the defending team an advantage, with an extra man in the lineout.
"Allowing the hooker to lift more at the front allows sides to defend more heavily at the back, which is a way of cutting down attacking options," Jones said.
The Ireland team to play Tonga is:
15 Girvan Dempsey (Leinster Terenure College) 14 John Kelly (Munster Cork Constitution) 13 Mike Mullins (Munster Old Crescent) 12 Jonathan Bell (Ulster Dungannon) 11 Tyrone Howe (Ulster Ballymena) 10 Ronan O Gara (Munster Cork Constitution) 9 Guy Easterby (Llanelli)
1 Justin Fitzpatrick (Ulster Dungannon) 2 Shane Byrne (Leinster Blackrock College) 3 Reggie Corrigan (Leinster Greystones) Captain 4 Leo Cullen (Leinster Blackrock College) 5 Paul O Connell (Munster Young Munster) 6 Simon Easterby (Llanelli) 7 Kieron Dawson (London Irish) 8 Eric Miller (Leinster Terenure College)
Replacements: 16 - Paul Shields (Ulster Ballymena) 17 - Simon Best (Ulster Belfast Harlequins) 18 - Donnacha O Callaghan (Munster Cork Constitution) 19 - David Wallace (Munster Garryowen) 20 - Brian O Meara (Leinster Cork Constitution) 21 Paul Burke (Harlequins) 22 - Gordon Darcy (Leinster Lansdowne)
G Legev, P Hola, J Ngaumo, J Payne, S Mafileo, T Alatini, D Palu; T Lea'aetoa, U Ma'asi, H Lavaka, M Nguamo, I Afeaki, N Nafahu, S Afeaki, U Latu.