(CNN)Lionel Messi, Luis Suarez and Neymar inspired Barcelona's treble-winning heroics last season, but on early evidence the superstar trio may need to beat their record 122 combined goals to have any chance of repeating that title success.
Spanish Super Cup: Barcelona embarrassed by Athletic Bilbao
1 of 6
2 of 6
3 of 6
4 of 6
5 of 6
6 of 6
Luis Enrique's side has now conceded eight goals in four days ahead of the start of the 2015-16 La Liga campaign, after being crushed 4-0 by Athletic Bilbao in the first leg of the Spanish Super Cup on Friday.
That defensive disaster followed Tuesday's 5-4 victory over Sevilla in the UEFA Super Cup, in which the Catalan side blew a 4-1 lead before prevailing in extra time.
The long trip to Georgia may have taken its toll on Barca, and the writing was on the wall as early as the 13th minute at San Mames Stadium when Mikel San Jose scored a spectacular opener from inside the center circle in Barca's half of the pitch.
Visiting goalkeeper Marc-Andre ter Stegen headed a clearance from outside his penalty area -- and San Jose controlled the ball before lashing a volley back over the German's head.
The second half belonged to veteran Bilbao striker Aritz Aduriz, who fired a hat-trick to leave Barca needing a near miracle in Monday's return leg at the Camp Nou.
The 34-year-old netted 24 goals last season, and showed he will again be a threat as he powerfully headed home a cross by young newcomer Sabin in the 53rd minute, pounced for a second on 62 and then wrapped up the scoring with a penalty in the 68th after a foul by Dani Alves.
It was sweet revenge for the Basques, who lost 3-1 to Barca in the Copa del Rey final on May 30, and gives Enrique plenty to think about before the two teams meet again in their opening Spanish league match at San Mames on August 23.
Messi had scored twice in Tbilisi as Champions League victor Barca overcame Europa League winner Sevilla, but the Argentine was twice denied by Bilbao keeper Gorka Iraizoz -- once from a free kick at the end of the first half, and then just before Aduriz made it 2-0.
Pedro Rodriguez started in the continued absence of Brazil's Neymar, who has the mumps, and he came closest to scoring for Barca when he hit the crossbar five minutes after the restart.
Pedro, who netted the winner against Sevilla, continues to be linked with English Premier League club Manchester United, which went top of the table Friday after a second successive 1-0 victory.
Young Belgium international Adnan Januzaj made the most of his starting opportunity up front alongside captain Wayne Rooney, as the 20-year-old scored the only goal with a deflected low shot in the 29th minute after being put in space by Juan Mata.
Meanwhile, former Barcelona coach Josep Guardiola made the perfect start to his bid for a third successive German league title as Bayern Munich thumped Hamburg 5-0 in Friday's Bundesliga opener.
Morocco defender Medhi Benatia scored a 27th-minute opener, then Poland striker Robert Lewandowski began the second-half demolition -- completed by a quickfire double from Germany forward Thomas Muller and a late effort from Douglas Costa, who started alongside fellow new signing Arturo Vidal.
Bayern, meanwhile, will face a big test in the second round of the German Cup after being drawn away to last season's Bundesliga runner-up Wolfsburg.