Wales boss Warren Gatland has warned Dan Biggar that his switch to Saints has put his international starting spot 'in some jeopardy'.
Biggar, who has 62 caps to his name, will move to Northampton from Ospreys this summer.
He will still be eligible to play for Wales but continues to face competition for the fly-half role from Cardiff's Gareth Anscombe and Scarlets' Rhys Patchell.
Both of those players are on Wales' summer tour, but Biggar has been rested.
And Gatland has told the 28-year-old he must hit the ground running at Saints next season if he is to feature for Wales.
"If you don't have the same preparation time and you're not released as frequently as the Welsh-based players, you're putting your selection in some jeopardy," said Gatland.
"The players understand that, they're not happy about it, but they're the ones who have made the decision to leave and play outside Wales.
"The latest one is Dan Biggar. He needs to be playing well for Northampton, the team needs to be playing well, because you want a fly-half coming from a team with confidence.
"He's aware of that. The ideal situation is to have players playing in Wales, but also them playing too, so there's a balance to be had.
"The conversation I have with players and staff - it's the same for both - is they have to make the decision that's best for them and their families.
"They take the risk by not playing in Wales and we've had a few players that have left."