The draw means second-placed Atletico Madrid could close the 12-point gap with Barcelona, who are on 74 points, if they beat Celta Vigo later on Saturday.
With the title practically assured after last weekend's 2-0 win over Atletico, Valverde fielded a radically different side to the team that won 1-0 at Old Trafford in Wednesday's first leg, making 10 changes and giving three players their league debuts.
Top scorer Lionel Messi was left at home for the game after being struck in the face by United defender Chris Smalling while Ivan Rakitic and Sergio Busquets were also rested and Gerard Pique and Luis Suarez were suspended.
Goalkeeper Marc-Andre ter Stegen was the only player who started at Old Trafford to make the starting line-up against Huesca, although Barca were boosted by the return of France forward Ousmane Dembele after a month out injured.
Barca midfielder Arturo Vidal was happy to admit that his side's minds were more focused on getting beyond the Champions League quarter-finals for the first time since 2015 than on the game they were playing on Saturday.
Midfielder Riqui Puig was one of Barca's debutants and the 19-year-old produced the best moment of an uneventful first half, picking out Dembele with a wonderful pass but the Frenchman dragged his shot wide.
Brazilian forward Malcom struck the post early in the second half and team mate Carles Alena missed the target from the rebound in Barca's best spell after the interval, while substitutes Philippe Coutinho, Jordi Alba and Arthur Melo could not improve the leaders' attacking threat when they came on.
Huesca desperately needed a win to keep up their slim hopes of avoiding relegation but they struggled to make much of an impact and stay rooted to the bottom of the standings with 25 points from 32 games.
In another La Liga match the same day, Atletico Madrid reduced the gap behind runaway leaders Barcelona to nine points by seeing off Celta Vigo 2-0 with goals from strikers Antoine Griezmann and Alvaro Morata either side of halftime.
