Werder Bremen 2-4 Chelsea: Blues sign off with final pre-season victory after goals from Eden Hazard, Oscar, Diego Costa and Pedro

Diego Costa, Oscar, Eden Hazard and Pedro goals gave Chelsea a final pre-season victory against Werder Bremen but defensive troubles will have worried manager Antonio Conte.

Two goals in the first ten minutes of the match from Hazard and Oscar gave the Blues a comfortable lead but Claudio Pizarro drew one back from the penalty spot. On the stroke of half-time, Costa scored Chelsea's third. 

In the second-half, Werder Bremen's Lennart Thy scored to make it 3-2 but Pedro wrapped up the victory in the dying moments. Chelsea start their Premier League campaign against West Ham on August 15 at Stamford Bridge.

Diego Costa celebrating Chelsea's third goal of the game with the provider Eden Hazard 

Costa pictured stroking the ball past Wiedwald for Chelsea's third goal 

Costa slots the ball past Felix Wiedwald during Sunday's match against German side Werder Bremen

Cesar Azpilicueta in action for the Blues during their last pre-season friendly before their clash against West Ham 

Conte wasn't taking Werder Bremen easily, naming a very strong starting line-up and that duly paid off, when Eden Hazard gave Chelsea an early lead in the 7th minute. Oscar found the Belgium winger inside and the Bremen defence gave Hazard loads of time and space outside the box to strike the ball past Felix Wiedwald.

You wouldn't have thought it was a pre-season game for the Blues after their electric start. Conte's side doubled their lead just two minutes later. A great move involving Hazard, Costa and Oscar was finished off by the Brazilian midfielder in the 9th minute. 

The German side, who finished 13th last season, nearly found a way back into the game through a brilliant strike from Zlatko Junujuzovic that hit the crossbar.  

Just as Chelsea looked like they were about to cause even more mayhem at the Weserstadion, the German club drew level from the penalty spot. 

Nemanja Matic was the offender and if this was a Premier League match, the Serbian midfielder would have seen red for bringing down Junuzovic. Pizarro took the spot kick and found the bottom left hand corner to make it 2-1 in the 32nd minute.

The fans at the Weserstadion were in for a treat. Worryingly for Conte, Chelsea started to give Viktor Skrypnyk's side a couple of chances to draw level. Just moments before half-time Clemens Fritz's close range effort was denied by Thibaut Courtois. 

On the stroke of half-time, the Blues doubled their lead again when Costa, slotted the ball past Wiedwald after Hazard found him clean through on goal.  

Brazilian midfielder Oscar tries to dribble round Wiedwald in the Bremen goal but is denied by the keeper

Cesc Fabregas being given his instructions by Antonio Conte as the Spaniard comes on at half-time for Chelsea

Chelsea's Hazard races away from Werder Bremen's Clemens Fritz during the first-half action

Costa was denied Chelsea's third by the on-rushing Werder Bremen defence, who blocked his attempt at goal

Chelsea players celebrate Oscar's (right) goal during their final pre-season friendly

Conte made a positive subsitution at half-time, bringing on Cesc Fabregas for Matic. Unsurprisingly, the tempo slightly dropped at the start of the second period as legs started to tire.

The best chance early on in the second half fell to the scorer of Chelsea's third, Costa. The Spaniard should have made it four but poked his effort just wide of the right hand post. 

Conte and his players must have been delighted with the ease of which they could carve open the Werder Bremen defence. Just minutes after Costa's effort, Oscar tried to dribble past Wiedwald but was denied by the goalkeeper's feet.

However, equally as worryingly for Chelsea and Conte was their defensive performance. 

Substitute Thy scored Werder Bremen's second goal of the match in the 65th minute, slotting his effort into the bottom right corner, leaving Courtois with no chance.

Oscar took his finish early, much to the surprise of Werder Bremen goalkeeper Felix Wiedwald. 

N'Golo Kante, who started his first game for Chelsea, battling for possession with Werder Bremen's Max Kruse

Nemanja Matic, who gave away the penalty for Werder Bremen's goal, attempting to tackle Bremen's Zlatko Junuzovic

Conte named a very strong starting line-up, leaving Cesc Fabregas (right) and Juan Cuadrado on the bench

With players starting to tire, Chelsea brought on Michu Batshuayi, Victor Moses and Pedro for Costa, Hazard ad Willian. Just after making these changes, John Terry worringly limped off for the Blues, only to be replaced by Michael Hector.  

The match fizzled out during the closing stages after a blistering start and more wholesale changes were made by Conte. Ruben Loftus-Cheek, Ola Aina, Nathaniel Chalobah and and Asmir Begovic came on for Cesar Azpilicueta, Oscar, N'Golo Kante and Courtois. 

The friendly was finished off with another goal, with Pedro managed to bag Chelsea's fourth, tucking the ball past Wiedwald.

Conte will be happy with the Blues attacking display but will know his side will have to sure up defensively. 

Antonio Conte and Viktor Skrypnk shake hands moments before seeing their teams involved in the high-scoring affair 

Oscar, who scored Chelsea's second goal at the Weserstadion, in action during the first-half