The pats on the back, the theory goes, are a greater danger than the blows to the chin. Leinster will be in no mood to rest on the veritable rainforest of laurels quite properly showered upon them in the aftermath a third European title in four seasons and with it affirmation of their status as the best of all-time.
They have one last assignment, the RaboDirect PRO12 decider in their own backyard at the RDS against the Ospreys on Sunday afternoon.
They can take it for granted that their opponents from across the Irish Sea will be fired up by another old boxing truism - the bigger they are, the harder they fall.
Leinster have no wish to end the Celtic season as they have ended the last two, finishing second in the Grand Final.
The winner-take-all showpiece, devised as a suitable climax to a campaign stretching back over nine months, has only been in operation, has only been in operation for three seasons.
Sunday's denouement at the RDS is a repeat of the first on the same weekend at the same venue two years ago.
Leinster, top of the table at the end of the regular season then as now, had lost their European crown the previous month in a semi-final at Toulouse.
Having seen Munster off 16-6 at home in the last-four play-offs, a second Celtic League success in three seasons would have been all the more welcome as compensation for their temporary separation from the Heineken Cup. Instead they fell to the Welsh birds of prey at the zenith of their game.
Before Leinster knew it, the Ospreys had swooped back across the sea to Swansea with the silverware, due reward for the best performance since their birth as a result of the shotgun marriage between Neath and Swansea when Wales went regional in 2003.
While the runners-up recovered to monopolise Europe and reach hitherto untouched peaks of excellence, the Ospreys staggered into deep recession along with the other Welsh regions.
Like one of those football teams forced to slash the wage bill by relegation from the Premier League, they off-loaded a whole host of big-name players.
Nine of the 19 on show in Dublin two years ago have either gone or are about to go - Mike Phillips, Lee Byrne, James Hook and Huw Bennett to France, Nikki Walker to England, Marty Holah back to New Zealand, Jerry Collins and Filo Tiatia to Japan. For Wales' Bath-bound prop Paul James, Sunday will be his swansong.
Last season, just a week after conquering Europe a second time by virtue of an unforgettable second-half come-back against Northampton in Cardiff, Leinster again found the double beyond them.
While Munster at Thomond Park proved a bridge too far, at least this time they are on home territory, although the same was true of Bayern Munich last weekend and a fat lot of good it did them.
Leinster are far too professional and smart to underestimate the hazards entailed in their last challenge of another wonderful season.
In reaching the Pro 12 final, the Ospreys blitzed Munster. As head coach Joe Schmidt says: "We know that anyone who can beat Munster 45-10 have to be a very good side."
And he will also point to what happened at the RDS one Friday night a couple of months back when Dan Biggar's touchline conversion of Richard Hibbard's block-blusting corner try edged the Ospreys home 23-22.
True, Leinster's line-up that night was a long way short of full-strength but the message had been hammered home - only the best will be good enough this time.
How the rejuvenated Ospreys have coped with a series of traumatic events and still emerged as worthy finalists is a tribute to their squad and new head coach, Steve Tandy.
At 32, the former flanker may be a novice but since taking over from Sean Holley in February he has presided over seven wins out of nine, including six on the spin since Dublin in March.
Tandy hasn't just got them winning but playing with a panache which has brought 21 tries in those six matches and just one from Shane Williams. The ageless magician even contrived to see Munster off in a puff of smoke without being obliged to pull anything unusual out of the hat.
He will have to go some if he is to cause a final sensation on Sunday before retiring at the age of 35. Leinster are something else and what they achieved at Twickenham last Saturday was considerably more than a dazzling demonstration of the total rugby which engulfed Ulster in the way it has engulfed everyone else.
Never in the course of one match has one team obliterated so many records and re-written as large a chunk of the history book. Three wins as captain meant Leo Cullen had overtaken Martin Johnson as the most successful skipper in the history of the competition, not that he will be heard saying a word about it.
The Untouchables have already been installed as 4-1 favourites to make it a European hat-trick next year when the final will be in Dublin.
Meanwhile, the Ospreys are hard at it, working out a way to create the giant-killing of the season…
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