Luka Modric gave Real the lead during a solid first half for Los Blancos, but Betis dominated after the break and deservedly tied things up through Sergio Canales.
The hosts seemed far more likely to find a winner, but it was Ceballos―against his former club―who bailed out his side with a fantastic free-kick.
Los Blancos had failed to win their last two outings in the competition.
Modric's New Role Key to Solving Real's Scoring Problem
Real manager Santiago Solari opted for an aggressive change of tactics on Sunday, introducing a 3-5-2 formation that changed to a 3-4-2-1 in possession and relied heavily on attacking in transition.
The formation change was likely in part because of the wave of injuries plaguing the team, but it worked wonders at times against Betis. The hosts struggled out wide and had a hard time finding an equaliser, despite going up against a number of backups and even Castilla players.
The most aggressive part of the formation was the new role for Modric, who almost played as an attacking midfielder, moving next to Vinicius Junior. Sports writer Dermot Corrigan noted he was remarkably high up the pitch when he scored, a beautiful curler on the rebound from the edge of the box:
Robbie Dunne also remarked the Ballon d'Or winner has been taking a lot of shots of late, in part because he's popping up in dangerous areas more often:
His role may not have led to tons of goals or chances, but it's worth noting he was playing without the likes of Gareth Bale, Lucas Vazquez and Marco Asensio. Karim Benzema also lasted just one half before he was taken off with what appeared to be a finger injury.
A lack of goals has been a major issue this season―Barcelona have roughly double the amount in La Liga―but the threat of Modric's shooting may just be what creates enough space for the rest of the team to do their thing.
Blancos Must Embrace Youth Movement in Lost Season
Unless things drastically go wrong this season, Barcelona are going to win the La Liga title yet again, making it four titles in five years. Their lead over Real is already up to double digits, and while Atletico Madrid only chase the Blaugrana by five points, they don't seem to have the consistency needed to overtake them.
Real's focus in the league should be on the top four, and even that could prove tricky given their wave of injuries. Benzema became the latest victim on Sunday, leading to the introduction of little-known Cristo:
The 21-year-old held his own, despite the difficult conditions―Villamarin is a daunting place to play even for veteran stars, let alone youngsters.
The 2018-19 La Liga campaign looks like a lost one for Real, but there are silver linings. Vinicius has been getting plenty of opportunities of late, in part because of the injuries, and Marcos Llorente's emergence as a genuine building block for the future happened only because of the absence of Casemiro.
Los Blancos may as well embrace the injuries and their struggles and go all out. They've been stocking up on young talent for years, and now is the time to give them minutes and see who they can rely on in the future.
Let the likes of Cristo, Jesus Vallejo, Brahim Diaz, Alvaro Odriozola and others do their thing outside of the Copa Espana, and save the stars for the UEFA Champions League and top fixtures.
Sevilla―who lost to Athletic Bilbao earlier on Sunday―and Deportivo Alaves have been excellent so far this season, but at least one of those teams is bound to drop off. A top-four finish shouldn't be hard to clinch even if the youngsters play a good chunk of minutes moving forward.
Real will face Leganes in the second leg of their Copa del Rey clash on Wednesday before hosting Sevilla on Saturday in a key clash for the top four. Betis visit Real Sociedad on Thursday in the cup and host Girona on Sunday.