Vitor Roque's maiden Barcelona goal saw the La Liga champions win their first match since manager Xavi's announcement that he is to depart as 10-man Osasuna were beaten 1-0 at the Estadi Olimpic Lluis Companys.
Roque, the 18-year-old Brazil forward recently signed from Athletico Paranaense, opened his Barca account with a header just past the hour mark, a minute after coming off the bench.
Despite having Unai Garcia sent off four minutes later, Osasuna showed some threat as they sought an equaliser but Barca were able to see out the win.
Xavi's men bounced back after successive losses in the Copa del Rey at Athletic Bilbao and Saturday's 5-3 home loss to Villarreal, after which the former Spain midfielder announced he would be leaving the club this summer, with the gap between them and leaders Girona reducing to eight points.
Ex-Barcelona striker Memphis Depay's last-gasp goal salvaged a 2-1 home win for Atletico Madrid against Rayo Vallecano which lifted Diego Simeone's side back to third in the La Liga standings.
Atletico moved up to 47 points, level with Barcelona but ahead on goal difference, with both clubs seven adrift of second-placed Real Madrid, who have a game in hand and play at Getafe on Thursday.
Defender Reinildo Mandava put Atletico ahead with a towering header from a Rodrigo Riquelme free kick in the 35th minute but a fine first-half strike from the edge of the box by Alvaro Garcia levelled the scores seven minutes later.
One minute into added time, Antoine Griezmann found Depay inside the six-yard box and the Dutch forward reacted quickly to secure victory for the hosts.
Additional reporting: Reuters
