Real Madrid travel to one of LaLiga's most difficult venues on Friday (21:00) looking to make it four wins from four, and José Mourinho was in no mood to underestimate the challenge.
"It has to be a great Real Madrid," the head coach said. "Betis are a very good team. To win, you have to be at your maximum level."
Mourinho also explained the departure of Ceballos, who terminated his deal by mutual consent, and made a return to Betis this week.
"We spoke for three minutes on the phone. I told him he wasn't in my plans," Mourinho said. "Players often stay attached to their contracts, but in this case things were straightforward because he told me he'd prefer to be free to decide his future. Within a couple of days, the player and the club reached this conclusion."
Asked about the standard of the league this season, Mourinho identified Atlético Madrid as the clearest challengers.
"Atlético will be candidates. They surely think and feel they can do it. That stability of the same coach and mentality is an important strength in football," he said. "Then there are Champions League sides like Betis or Villarreal who are strong, we'll see tomorrow.
"The Basque clubs too, everyone is difficult. For me it isn't an easy league. There's a pressure here that doesn't exist in other competitions, which is having to win always. In Germany or France they have the peace of mind of knowing they'll always be champions. Here, a result that isn't a win isn't a good result."
Friday's fixture also brings a reunion with Manuel Pellegrini, the Betis manager Mourinho faced as a rival during his time at Chelsea and Inter Milan.
"I never reproach anything because we can't go back in time," Mourinho said. "There's such a long history in football that there are things you say and do that make you feel like an idiot, that make you feel wrong. I've made some stupid comments.
"If he hears them, he'll laugh, because I paid for it, for example, with the Chelsea title race. He's had moments of great class with me too — in a Betis-Roma friendly, with a referee who loved Betis, we were down to seven men on the pitch and he told his players not to destroy us. They could have scored eight and scored three. A great example as a coach and as a person."
On the club's academy graduates, Mourinho said several train with him regularly and praised the money the club has recouped through sell-on clauses on departed youngsters, adding that injuries and suspensions would open further opportunities for them as the season progresses.
He also gave an update on Sergio Martínez, who has trained with the first team for two days: "He has potential and a little experience in the top flight. He has to work, but the level of quality and intensity here is different."