Isco converted from the penalty spot in the 88th minute and Borja Mayoral scored a header in stoppage time to give Numancia a near impossible task in the second leg at the Bernabeu on January 10. He said: "There have been changes from the last La Liga game but numerous players who played today have been playing and doing well".
"They will come to play and we will too. We scored two goals from the penalty spot but they all count", Real defender Nacho Fernandez told reporters.
Barcelona have found Celta to be a bogey team of late, losing on their last two visits to Balaidos, while the LaLiga game between the sides at Camp Nou last month ended 2-2.
Barca B striker Arnaiz, leading the attack in the absence of star names Lionel Messi and Luis Suarez, scored in his third successive cup appearance when he finished off a low cross from Andre Gomes.
Denmark global Pione Sisto levelled for Celta in the 31st, smashing the ball into the roof of the net after Iago Aspas had hit the underside of the crossbar.
Manager Ernesto Valverde has made a decision to be patient as he re-introduces the Barcelona star back into the squad, as he returns from an injury.
Por error, anuncian a Coutinho en Barcelona
Salió de inicio y fue sustituido por Ragnar Klavan en el minuto 89 del encuentro. Son dudas al menos para el próximo partido con Everton".
Barca hit the woodwork twice, Sergio Busquets crashing a shot against the bar and Sergio Roberto striking the post in stoppage time while Turkish global Emre Mor went close to grabbing a victor for Celta.
Barca's record-signing Ousmane Dembele came on in the second half to make his first appearance since rupturing his hamstring in September and almost scored the victor, but his low shot was saved by Celta goalkeeper Sergio Alvarez. I'm happy with the squad I have.
"Celta pressed high and took risks, they were risky on the counter-attack, but so were we".
"I'm happy we kept a clean sheet".
"We must take into account that the pace of a whole match against a first division team".