Police were called to Haringey at about 1.20am on Saturday where they found Mr Mendes suffering from multiple stab wounds.
The 25-year-old, who had lived in the UK since 2015, was taken to an east London hospital but was pronounced dead about an hour later.
Met Police said that although formal identification had not taken place officers were confident the victim was Mr Mendes, who had been living in Tottenham, north London.
His next of kin have been informed and a post-mortem examination will be carried out in due course, the force said.
Two teenage boys aged 15 and 16 were arrested on Sunday on suspicion of murder in connection with the stabbing and were still being questioned on Monday afternoon.
Detective Chief Inspector Glen Lloyd urged witnesses who saw the attack or events leading up to it to contact the police.
He added: "Although we have made two arrests, our investigation continues to gather pace.