Xabi Alonso described Liverpool as “a complete team” after he endured a painful return to Anfield with Bayer Leverkusen in the Champions League.

The former Liverpool midfielder suffered the joint-heaviest defeat of his Leverkusen reign as Luis Díaz struck a hat-trick for Arne Slot’s side, who now sit top of both the Champions League and Premier League tables. All of Liverpool’s goals came in a devastating second half display that extended Slot’s outstanding start to 14 wins in 16 matches.

“I think they are a complete team,” said the Leverkusen coach of his old club. “They are able to defend, to score, they have power in both boxes, they can keep clean sheets and they are able to score with not many chances.

Related: Díaz hat-trick dashes Alonso’s hopes on Champions League return to Liverpool

“That is a great strength in the Champions League, especially in the next round. They have this power but it is still too early to tell. The team has a good balance. The coach is doing great work so far. It’s looking a promising season but we are still in November.”

Alonso was afforded a warm reception from Liverpool fans, but admitted the severity of the loss made it a difficult night.

He added: “I have bitter feelings with the game which mean I can’t enjoy the reception too much, but I really appreciated it and was thankful that even after so many years that I come here and I have this bond with the club. It was nice but it would have been nicer with a better result.”

Slot’s decision to deploy Díaz as a central striker paid dividends as the Colombia international struck the first hat-trick of his Liverpool career.

The Liverpool head coach said: “I only have four strikers available at the minute and with the fixture list it is almost impossible to play them all the time. And I think [Jonathan] Tah is one of the best defenders in Germany, if not the best, and he likes to play against a target man so I chose to play Lucho [Díaz] from the left and the middle to surprise him with runs in behind. What a pass from Curtis Jones [for Diaz’s opening goal].”

Slot’s start is the best made by any new manager at a Premier League club and he admitted to embracing the pressure of being Liverpool head coach.

He said: “If you work at any club there is always pressure. We embrace this pressure because that’s what we want, to compete for everything. If you work or play for Liverpool then you have to accept that. The other side is if you work or play here then you can enjoy incredible evenings like this and enjoy it. Last Saturday the atmosphere was impressive, but this was even more impressive.”