Lionel Messi came off the bench to score the only goal against Levante at Camp Nou, ensuring Barca retained their top-flight crown by moving nine points clear of Atletico Madrid – against whom they boast a superior head-to-head record – with three games to go.
"We are happy, but we still have challenges ahead," said the Barca coach, with Liverpool the visitors on Wednesday in the first leg of their Champions League semi-final.
"Winning the title with distance and with margin are things that with the competitors we have is difficult."
Messi was named on the bench for the second match running but came on at the interval for profligate former Liverpool star Philippe Coutinho.
The Argentinian superstar made the difference, breaking the deadlock in the 62nd minute to finally puncture the dogged resistance of the relegation-threatened visitors.
"It was clear that Messi had to play at least 45 minutes," added Valverde.
"We have a match on Wednesday and we must be active and at the end he has scored the goal because we already know that Leo scores goals everywhere."