Barcelona head coach Ernesto Valverde believes an unpredictable weekend in LaLiga means his side cannot rest on their laurels at the top of the table.
Lionel Messi and Paulinho were on target as Barca overcame Valverde's former club Athletic Bilbao 2-1, while bitter rivals Real Madrid suffered a shock 2-1 loss at Girona.
That result left Barcelona eight points better off than the champions, with Valencia sitting as their nearest challengers in second, four points off the pace.
Marcelino's side battled to a 2-1 win over basement boys Alaves, while Atletico Madrid added to their recent glut of draws against Villarreal.
"LaLiga is complicated, it's a difficult league that we play in," said Valverde at a news conference ahead of Tuesday's Champions League Group D match at Olympiacos.
"We had to suffer to win at San Mames the other day, Madrid lost in Girona, Atletico Madrid only drew with Villarreal.
"Valencia are second and they struggled to beat Alaves. Every point is hard to get. You have to work hard to win every game.
"This is a weekend that has shown how hard it is to win in this championship and how hard it is to win games."
Valverde was then asked, with no little mischief, whether Valencia now represented a greater threat to their title ambitions than Real Madrid.
"We're worried about all of them and none of them," he replied. "Of course, they are the opponents that are directly behind us, but it's not a question of being worried. We only worry about ourselves
"We need to win our games and not look over our shoulders. These are only early days and this is not a definitive advantage.
"Obviously Real Madrid and Atletico Madrid are the most natural rivals but Valencia are having a great season, Sevilla as well."
Barcelona will secure their place in the last 16 if they better Sporting CP's result against Juventus, although Valverde has concerns at centre-back.
Gerard Pique is suspended following his red card in the reverse fixture, while Javier Mascherano's foot problem will be assessed.
"Since the game at Murcia, Mascherano has had a foot infection. We need to have a look at that," added Valverde.
"We'll look at him in training today and find out how he is.
"[Thomas] Vermaelen as well had some fitness issues but he's been declared fit.
"Hopefully they can play tomorrow but we have a training session coming up where we can sort out those issues."
Valverde won the Superleague Greece three times, completing the domestic double twice, across two spells in charge of Olympiacos and is looking forward to returning to the Karaiskakis Stadium, where he has many fond memories.
"I'm sure that although they will welcome me very warmly they will be supporting their team tomorrow," he said of the Olympiacos faithful.
"There were some very special games when I was here. The games where we won the league here, played in the Champions League against big teams and Greek Cup finals. Unforgettable games – I couldn't say just one.
"It's not just Olympiacos fans but Greek fans in general are very different perhaps to fans in other countries.
"The fans come and really have a party. There is passion, not just in part of the stadium but all over. We will feel that when we go out on the pitch."
