Real Madrid's fine young side are in form. Tuesday's 1-0 victory against Espanyol in the Copa del Rey meant Carlo Ancelotti's side have gone eight games without conceding a goal for the first time in their 112-year history.
Iker Casillas has not conceded in 659 minutes, another new club record. The Espanyol clean sheet saw him overtake 60s 'keeper Araquistain as well as Francisco Buyo in the 1994-95 season. How his situation has changed from a year ago when he couldn't get in the team.
Madrid, who briefly topped the table at the weekend before Barca and Atletico won their Sunday games, face their toughest test to that record on Sunday in the Basque Country.
They travel to Athletic Bilbao's new San Mames home for the first time, a home where Ernesto Valverde's side remain unbeaten in the league - though they lost at home to Atletico Madrid in the Copa del Rey on Wednesday night. Athletic have a better home record than Real Madrid and they're the only team to beat Barcelona this season.
They've managed to sort their away form too, putting a five-point gap between themselves in fourth and Villarreal in fifth. With Barca, Atletico and Madrid so clear of the rest, there's one race for the title and another for fourth.
The new stadium may only have three sides and a 38,000 capacity at present, but the fourth side is going up and should be ready for next season, when the seats will rise to 53,000. Their much loved San Mames home may have been historic and led to a tearful departure, but it was cramped and had more pillars than the acropolis. The Lions’ new den, right by the old one on the banks of the Nervion River, is fit for Champions League football.
I recently travelled to Bilbao to meet their attacking midfielder Ander Herrera, 24. He's a bright boy who was playing well enough to elicit a bid from Manchester United in August. He's happy where he is for now, thriving too.
Herrera trained as a journalist, but he was too good at football to continue. He didn't want to be a sports journalist, but to work with nature.
"I really like National Geographic," he explained. "I watch and read it every day. I’m curious, interested and afraid of the shark. I’m not sure I could do the shark cage. I like photography too. I want to go on safari to Tanzania and Kenya, but the problem I have is that I fancy going with my mates. I’m sure my girlfriend would appreciate that!"
Herrera loves his new club in the city of his birth, but he grew up as a match-going Zaragoza fan. Their fans consider him one of their own, their ultras have flags calling him an idol, but he's also a footballer who wants to play at the best level possible. That's not Zaragoza in Spain's second division, though he didn't engineer a move. They were in financial trouble and accepted a €10 million (£8.2m) bid for him.
He's happy where he is; he states proudly that, "The kids around here don’t support Real Madrid or Barca, they support Athletic" and explained what represents a good season for the Basque giants.
"There’s nothing more beautiful than playing in Europe," he said. "When I watch the Champions and Europa League, I have a healthy envy. Our ambition is Europe and the top six-seven; our dream is the Champions League. I understand why our fans demand that of us because we earn good money."
It looks like that dream will come true under their excellent coach Valverde. He's not a madcap genius like Marcelo Bielsa, the man he replaced. Bielsa told Herrera that he could be one of the best players in the No. 10 position, but he also played him as a 6 (think Busquets) and an 8 (Iniesta, Xavi).
Bielsa was a success at Athletic, but Valverde has given the team more consistency. He's a thoughtful coach who takes no nonsense and sees that his teams play good football, which they are doing at their new home. Herrera was sad to leave San Mames last year.
"It was very emotional for the older fans," he explained. "Heart-wrenching. For me the old stadium was very nice. I like the traditions in football, so I appreciated the history of the place. I know I'm only young, but I've been watching football since I was two because of dad.
"I watched [legendary Basque goalkeeper] Iribar on the last day at the stadium. Iribar, he’s the image of the club, like Di Stefano in Madrid. He told me that he couldn’t bear to see the cathedral [as it was known in Bilbao] torn down. It smelt of football."
Herrera likes their new home.
"The new stadium is like the Emirates at Arsenal, but steeper," he says. "Wait until it is finished, the noise will be incredible."
It will still be incredible on Sunday when Madrid visit.
"Real Madrid?" Herrera smiled. "The least loved team here. There’s very, very little love for them here.
"With Barca, there’s more respect. It’s also a political question, the Basque country and Catalonia. The feeling for Atletico Madrid is somewhere in between. With Real Sociedad there's more empathy."
Herrera hopes to show the world his quality and for the unbeaten run to continue; Real Madrid hope for another clean sheet.
Both desires could be sated with a 0-0, but the chance of either team going in search of that is minimal. Not in Bilbao, not against Real Madrid.
Andy Mitten - @AndyMitten