Chelsea's Marcos Alonso can be world's best left-back - Maurizio Sarri

LONDON -- Maurizio Sarri backed Marcos Alonso to become the world's best left-back if he improves defensively after he played a key role in Chelsea's 2-0 win over Bournemouth at Stamford Bridge.

Alonso came closer than anyone to breaking the deadlock in a frustrating first half for Chelsea when his right-footed shot bounced off the post, and he played decisive passes in the build-up to Pedro and Eden Hazard's goals in the final 20 minutes as Bournemouth's stubborn resistance crumbled.

Those contributions took Alonso's tally to one goal and two assists from Chelsea's first four Premier League games at the end of a week that saw him named in Luis Enrique's first Spain squad for matches against England and Croatia later this month.

"Alonso, at the moment, in this position at left-back is maybe the best in Europe," Sarri said. "[His] physical qualities are at a top level, I think. He's doing very well in the offensive phase. But I also think he can improve in the defensive phase. If he improves that, he could be the best left-back in the world."

The win marked Chelsea's sixth time winning their opening four Premier League matches. Four of those sides were crowned champions, but Sarri was in no mood to indulge talk of the title so early in the season.

"I think that now, for us it's better to think about the next match," he said. "The gap at the beginning [to Manchester City] was 30 points [from last season]. I think it's very difficult to recover this gap in only one season. I'm very happy with the four matches, but I think only, starting from now, about the next match. Not until the end of the season.

"I am happy with the result and I am happy with the performance. It was a very difficult game. [Bournemouth] are very organised defensively, and defended very well. In the first half, the situation was difficult. Maybe we needed to move the ball at another speed, and maybe more movements without the ball. But in this kind of match, usually you can win in the last 20-25 minutes, so I was always confident."

Asked if Chelsea have surpassed his expectations with their perfect start, Sarri said they have.

"At the moment, I'm very happy with my players," he said. "They improved very well during the week and in matches. I'm really very happy to have 12 points from four matches, but I always think we can do more. We can improve. Especially in the performance, of course. We can improve."

Chelsea's win masked another difficult day for Alvaro Morata, who was largely ineffective before being replaced by Olivier Giroud in the 61st minute.

"It depends upon the situation on the pitch," Sarri said of his decision. "At the moment, we crossed three, four, five times, so I thought Giroud, in that moment, was better. Only for this. It depends upon the situation.

"Alvaro is improving. Maybe he needs more space, but I am lucky because, in this situation, Giroud is very useful."