Rangers' next Europa League opponents, Athletic Club, dropped points in La Liga over the weekend.
Ernesto Valverde's men hosted 14th-place outfit Osasuna at San Mames on Sunday evening.
Despite registering 11 shots, five of which were on target, Athletic failed to score as the sides played out a goalless stalemate.
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Although they only picked up a point, the Basque outfit remain fourth in Spain's top flight, which, at the end of the campaign, would earn them a place in next season's Champions League.
They travel to Ibrox a week on Thursday for the first leg of their hotly anticipated Europa League quarter-final tie with Rangers.
Barry Ferguson's side then visit San Mames a week later, although Athletic face Rayo Vallecano on the Sunday in between.
Indeed, after the return leg, too, the Spaniards take on the might of Real Madrid at the Santiago Bernabeu.
Boss Valverde has bemoaned their fixture schedule and lodged an official complaint to the league: "We're going to play Rangers at home on Thursday, Real Madrid on Sunday, and then play Las Palmas again on Wednesday," he said.
"So we have to play three of our most important games of the season in just six days? Why not seven?
"We have complained to La Liga. It's an issue they have to look into."
