It's no coincidence that the two overlap because this tournament is going to be a factor in selection.
The days of the Six Nations as the exclusive vessel for gaining a place on the Lions party is long past.
Consider this weekend for example. Johnny O'Connor of Wasps may not be in favour with Eddie O'Sullivan, the coach of Ireland (and a likely Lions coach) but this Sunday's clash between his team and Biarritz is a showpiece chance to shine in front of Lions boss, Clive Woodward.
If he can get the better of Serge Betsen he is going to be a contender, whether he plays Six Nations or not.
But the tournament (although its role as feeder for international teams is important) is primarily about teams chasing the crown of Europe's best. Last year saw the tournament soar to new heights from the semi-final stage onwards.
This year we are hoping for a fizzing tournament from day one when the Scarlets meet Toulouse, the stylish runners-up last season.
It's always a joy to witness cross-country clashes, games like Gloucester and Cardiff are a real and irresistible throwback for some, while the chance to see the French elite is another allure.
What would be wonderful for the tournament and the game in Europe would be for Italy to have a team reach the knockout stages for the first time.
Edinburgh achieved the feat for Scotland last year but this might be a wish too far. Maybe I'll stick with the wish for another outstanding competition. That shouldn't be asking too much…