The early leaders of the Spanish league rolled over newly- promoted Valladolid at home on Saturday, with Robert Lewandowski, Dani Olmo, Jules Koundé and Ferran Torres also finding the net.
Lamine Yamal, who starred in Spain's European Championship title run, set up two goals and was way too much for Valladolid to handle from Lionel Messi's old spot on the right flank.
Raphinha had already started the season strong with a pair of assists before he powered the big win over Valladolid with his first career treble. That came after the club was reported to have been interested in securing a blockbuster transfer for Athletic Bilbao winger Nico Williams.
If Williams had arrived, Raphinha would have likely been the odd man out.
"I have been working hard since I came back from the summer holidays. I knew that this season would be very important," he said.
Raphinha hurdles Valladolid's goalkeeper Karl Hein in scoring his side's fifth goal. (AP PHOTO)
"The game today showed that we don't need new players to come in. We are in good shape and working hard in practice and games."
It was 3-0 by halftime and the final score could have been even worse for the hapless visitors. Olmo, making his first start for Barcelona, hit the woodwork twice and had a goal waived off for offside, while Lewandowski also rattled the post.
When Barcelona fired Xavi Hernández and brought in Flick, president Joan Laporta said his team needed a change.
So far, so good.
The German coach has found a slick attacking unit of Lewandowski, Raphinha and Spain trio Yamal, Olmo, and Pedri, giving their fans reason to hope Barcelona will challenge defending champions Real Madrid despite their addition of Kylian Mbappé.
Flick continued to dip into the well of Barcelona's youthful talent and gave a fourth debut to the products of the club's famed La Masia academy, bringing on 19-year-old defender Sergi Domínguez.
Raphinha used his chest to control a lobbed pass by 17-year-old defender Pau Cubarsí and opened the scoring in the 20th minute.
Lewandowski quickly doubled the lead from a cross by Yamal to give the Poland striker four goals in this campaign.
Koundé put the result beyond doubt in first-half injury time.
Raphinha scored from passes by Lewandowski and Yamal in the 64th and 72nd to make it a blowout. Olmo then took this second goal in as many games since joining from Leipzig. Substitute Torres capped the demolition by side-footing in a low cross from Raphinha.
Barcelona have 12 points to Madrid's five. The titleholders are in fifth place after drawing two of their first three matches. They host Real Betis on Sunday.
Substitutes Ángel Correa and Alexander Sorloth linked up in injury time to secure a 1-0 win for Atletico Madrid at Athletic Bilbao.
Correa took the late winner after Sorloth sprung a counterattack when he stole a ball from defender Iñigo Lekue and set up his strike partner on the gallop to round the goalkeeper and score.
