There are few tournaments in the world in which momentum plays a greater role than the Six Nations, which starts Saturday.
In a competition that sees the Grand Slam, where all five opponents are defeated in one glorious sweep, as the ultimate aim it is understandable.
Alan Gaffney always used to say that you could not win a Grand Slam in the first week, only lose one. Given the Australian-born coach orchestrated Ireland's first clean sweep since 1948 in 2009 he should know.
And momentum can easily paper over the fault lines in teams, or even lift a squad out of rut.
Look at the performance of England and Ireland in last season's tournament.
England were the laughing stock of the rugby world after their antics at the 2011 World Cup in New Zealand. Martin Johnson, a former captain and talisman, had resigned as coach while Mike Tindall, the captain, had been caught in a bar with a woman that was not Zara Phillips, his newly married royal wife.
The team, which exited the tournament at the quarter-final stage, was underperforming and after Johnson resigned they were headed by an interim manager in Stuart Lancaster.
They subsequently finished second to Wales in last season's Six Nations and used that effort to swing on an ever increasing arc of improvement that culminated in November with a thrashing of New Zealand, the world's best team.
Wales also found redemption in the World Cup by winning the Grand Slam after suffering a painful defeat by Australia in the third place play-off.
Drawn to play Ireland in Dublin in the first round, the Welsh secured a thrilling 23-21 victory with a last-gasp penalty. The momentum generated from Leigh Halfpenny's final-minute penalty propelled Wales through the competition and on to glory.
Oh how they need a similar outcome in Cardiff on Saturday. Rob Howley's Wales are languishing on a run of seven consecutive defeats, their worst since 2003.
Scotland are in a similar situation, having seen Andy Robinson, their previous coach, resign after the catastrophic defeat to Tonga in the autumn.
Under the interim management of Scott Johnson, Scotland start out in London against England having won only one of their first round matches in the tournament since Italy were admitted in 2000.
Scotland's sole first-round success was against France, beating Les Bleus 20-16 at Murrayfield in 2006. Scotland went on to finish third that year with six points, their best effort in the new format.
It just goes to show that anything is possible if you win in the first round. It is make or break this weekend.
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