Gareth Bale's Real Madrid comeback this week has proved to be short-lived after head coach Zinedine Zidane confirmed he would miss Saturday's LaLiga match against Athletic Bilbao with another calf complaint.
Bale had not featured since scoring in September's 3-1 Champions League win at Borussia Dortmund due to calf and groin injuries before being introduced as a second-half substitute during Tuesday's Copa del Rey fourth-round tie against Fuenlabrada.
It proved to be a dazzling cameo, with the Wales star creating both goals for Borja Mayoral in an otherwise laboured 2-2 draw with Madrid's third-tier opponents that closed out a 4-2 aggregate win.
But the 28-year-old, who has been ravaged by fitness problems over the past two seasons once again felt soreness in his troublesome calf muscle and Zidane is not willing to take any undue risks for the trip to San Mames.
"It's nothing serious, it's just a niggle and when it's a little niggle we just don't want to risk anything," Zidane told a pre-match news conference.
"I can't tell you exactly when it happened, [some time] on the day of the game, when he suddenly stated having pain.
"At the end he started feeling a little bit of pain in the bottom of the calf and that was it."
Although he played down the severity of the injury, Zidane was unable to offer guarantees that Bale will be available for next week's match against Sevilla - Madrid's final LaLiga game before departing to the UAE for the Club World Cup.
"It depends on him, definitely. I can't give you a date. I just hope he's ready for next week," he said.
"The problem with Gareth is that he has to be 100 per cent fit to play. He can't feel small niggles.
"He's a very powerful, strong player and when it's something in his calf, as it has been, it's something complicated and we recognise it as a problem."
Zidane added: "We try to be positive with him. It's a bad moment right now but things will get better.
"We just have to help him and make sure he gets back to fitness. We can't forget that he's a very important player for us.
"When he's fit he's a great payer so we have to be patient. I believe in Bale, we all do. We're always supporting him and we hope that things will go well for him quickly."