Scotland head coach Gregor Townsend describes Saracens' schedule as "ridiculous" and says it has affected his Six Nations squad selection.
The English champions play Harlequins six days before Scotland's tournament opener against Ireland on 1 February.
Townsend has chosen Saracens' Sean Maitland but Duncan Taylor misses out.
"We're training five sessions from Monday 20 January to Monday 27 and those Saracens players can only make one of those sessions," Townsend said.
"It's not Duncan's fault or Sean's fault or Saracens' fault. But to have a fixture the Sunday before a Six Nations - none of the England players will be playing, they're away in a camp in Portugal the whole week - does make it really difficult for us to prepare the team as best we can."
Scotland players convene in Edinburgh on Sunday before flying to Spain for a warm-weather camp seven days later.
Under World Rugby regulations, players must be released from club duty five clear days before the start of the Six Nations.
A deal between England's Rugby Football Union and top-flight clubs allows Eddie Jones access to his Test players outside of designated windows.
Eight of Townsend's 38-man squad, including new captain Stuart Hogg, play in the English Premiership.
Gloucester lock Alex Craig and centre Chris Harris, London Irish prop Allan Dell, Worcester Warriors back-row Cornell du Preez, Northampton Saints centre Rory Hutchinson, Sale Sharks back Bryon McGuigan and Saracens' Maitland all ply their trade south of the border.
Townsend has selected experienced wing Maitland, but says the club's fixture list dented 30-year-old centre Taylor's hopes of reclaiming his berth.
"We rate Duncan very highly," Townsend added. "But unfortunately, Saracens play Sunday-Sunday the next week which to me is ridiculous, that a Premiership have got a game six days before we play Ireland.
"Duncan's been unlucky in that regard. The fact we know he's only going to make one of those five sessions means we've not included him this time."