Cesc Fabregas and Lionel Messi netted braces as Barcelona beat Osasuna 4-0 in the first leg of their Copa del Rey series on Wednesday.
With Messi starting on the bench and David Villa out with a broken leg, former Arsenal captain Fabregas scored off passes from Xavi Hernandez in the 14th and 19th minutes to take his goal tally to 13 goals in all competitions this season.
Messi, who was a last-minute inclusion in the squad after recovering from the flu, went on after halftime.
Showing no signs of illness, Messi headed in Fabregas' cross in the 72nd and capped the win in stoppage time.
The second legs of the round of 16 will be played next week.
Barcelona latest win added to its more than impressive numbers on the season.
Pep Guardiola's team has outscored opponents 37-1 in eight straight victories since losing 1-0 at Getafe and hasn't conceded a goal in 12 straight home games while scoring 53 times.
Even though earlier in the day Barcelona had said Messi would miss the match because of the flu, he entered in the squad as a substitute after ''responding well to treatment,'' according to the club.
Pedro Rodriguez and young winger Isaac Cuenca accompanied Fabregas in attack, and Guardiola opted to deploy a three-man defensive line that freed Dani Alves to play on the right flank.
The speedy Brazil defender had the hosts' first shot six minutes in and provided a constant threat throughout.
Osasuna came out pressing far up the pitch despite recent memories of the 8-0 rout it suffered in its first visit to Camp Nou in league play earlier this season.
But Barcelona's possession-based passing game soon pushed the visitors into their own area and crushed any thoughts of a surprise.
The European champions broke through when Xavi completed a great team buildup by finding the unmarked Fabregas on the left side of the area to slot by Osasuna goalkeeper Asier Riesgo.
The two Spanish internationals combined again shortly after as Fabregas took a pass from Xavi inside the edge of the area, turned to lose a defender, and beat the oncoming Riesgo with an exquisite chip shot to double the lead.
Ahead in the score, last year's runner-up pressed to finish off the series with Riesgo saving shots by Thiago Alcantara, Carles Puyol and Alves before halftime.
Messi went on for Pedro to the cheers of the home fans in the 59th and saw his chip try bounce wide after Alves played him through the defense.
But Riesgo could only look on when Messi rose up to redirect Fabregas' pass into the back of the net minutes later.
The Argentina forward finished off the rout late when he took Xavi's pass and fired in a left-footer for his 31st goal of the season in all competitions.
Barcelona will meet Real Madrid in a rematch of last year's final in the quarterfinals if both teams win their last 16 ties.
Earlier, Imanol Agirretxe scored one goal and set up another to lead Real Sociedad to a 2-0 win over Mallorca.
On Tuesday, defending champion Madrid staged a second-half comeback to edge Malaga 3-2 while three other topflight teams failed to beat lower-division opponents. Third-division Mirandes beat Racing Santander 2-0, second-division Alcorcon downed Levante 2-1, and third-tier Albacete drew 0-0 with Athletic Bilbao.
Valencia hosts Sevilla while Espanyol visits Cordoba on Thursday.
