Zinedine Zidane refused to put a time frame on Cristiano Ronaldo's injury absence after the forward was substituted at half-time in El Clasico.
Ronaldo had cancelled out Luis Suarez's opener in an entertaining 2-2 draw at Camp Nou, but he picked up an ankle knock while tapping from close range.
With the Champions League final against Liverpool three weeks away, Zidane insisted it was too early to speculate about the extent of the injury.
"I don't know how long he'll be out," the Frenchman told Real's official website.
"He said it wasn't much, but we'll see tomorrow.
"We'll do some tests to see the extent of the damage done to his ankle. He was a little worried because it was a bit swollen, but he said that it's nothing serious."
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Barca had Sergi Roberto sent off in first-half stoppage-time following a clash with Marcelo, but regained the lead through Lionel Messi seven minutes after the interval.
Gareth Bale then curled home a first-time effort with 18 minutes remaining to leave Real three points behind city rivals Atletico in the race for second, albeit with a game in hand.
"I'd have liked to have won," added Zidane.
"There was nothing at stake but it was a good Clasico - high intensity and chances. They played well and so did we.
"Everyone who likes football can be happy with a game like that. Football is always more important than the controversy that you want to create.
"We had a good opportunity to win today, clearly, we had a lot of chances to score, especially in the first half. In the end it was a draw and that's that. There are two games left and, in the end, Barcelona will finish the season unbeaten."
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Last updated at 1000 BST 07/05/2018.