Chelsea suffered their second defeat of the young Premier League season after giving up an early lead to go down 2-1 to Southampton at St. Mary's Stadium on Tuesday.

Raheem Sterling put Chelsea in front in the 23rd minute with his third goal in two games but Southampton leveled within five minutes with a spectacular strike from 18-year-old Romeo Lavia. In first-half stoppage time the home side took a lead they would not relinquish courtesy of a deflected effort from Adam Armstrong.

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The result means Chelsea drop to eighth and below Southampton in the Premier League table after suffering their second defeat in five games to start the season. Both teams have seven points to their name.

"We started well in all the games almost but obviously we are struggling with our focus and consistency in matches," Chelsea boss Thomas Tuchel said. "We struggled to find answers and find the way back if things don't go in our direction."

Yet Chelsea began the game brightly and could have taken an even earlier lead. Sterling failed to make the most of two openings in the Southampton box, first dispatching a tame shot at goal and then being denied by a saving tackle after opting to go alone rather than making the most of his side's numerical advantage on the break.

At the third time of asking, though, the summer signing from Manchester City made no mistake. After Southampton were left exposed by a smart Chelsea move down the left, Mason Mount slid the ball across the box and, despite a momentary intervention by Romain Perraud, Sterling was able to turn and find the back of the net.

Despite Chelsea's early superiority, their lead would be short-lived. Left free on the edge of the box following a half-cleared corner, Lavia scored his first senior goal in some style with an unstoppable drive past Edouard Mendy. The goal marked the first time a player born in 2004 had scored in the Premier League.

Just before half-time the hosts had the lead. Chelsea's defending left something to be desired as Perraud drilled a low ball into the box where Armstrong was left unmarked as his left-foot shot took a slight deflection off Chelsea defender Kalidou Koulibaly to help it past Mendy and into the top corner of the net.

"We knew it would be a tough night tonight. Chelsea are a tough opposition but the lads dug deep," Armstrong said.

"Nights like this we won't forget. It was frustrating on Saturday [against Manchester United], we had a few chances. That is football. We dug deep tonight."

It was Southampton that twice came close to extending their lead in the second half. Two last-gasp defensive efforts by Chelsea, from Marc Cucurella and Thiago Silva, were required to keep the deficit to just a single goal.

After starting with four at the back, Tuchel made a triple substitution and a move to a back five midway through the second half, bringing on Christian Pulisic -- as a right wingback-- as well as Ben Chilwell and Armando Broja.

But the changes did little to improve a disjointed Chelsea performance as they went down to a defeat that means they are already playing catch up to the teams at the top of the table.