Willian dismissed the prospect of a January move from Chelsea after his strike earned a 2-1 win over Newcastle on Saturday.
The Brazil playmaker, who joined from Anzhi Makhachkala in 2013, was linked with a £50million switch to Barcelona earlier this week.
Blues head coach Maurizio Sarri on Friday insisted it was "impossible" to lose Willian.
And the 30-year-old showed his value to Chelsea by scoring the goal which has given the Blues a six-point cushion over fifth-placed Arsenal in the race for Champions League qualification.
"My future is at Chelsea," Willian told BT Sport.
Sarri afterwards repeated his view on Willian, who has 18 months remaining on his current contract, but Chelsea could be busy in the winter transfer window, nonetheless.
Cesc Fabregas completed his move to Monaco on Friday and Sarri wants a replacement but is uncertain if, or when, a new recruit will arrive.
Cagliari's Nicolo Barella and Leandro Paredes of Zenit St Petersburg have been linked with moves to Chelsea.
Sarri's need was emphasised against Newcastle as Jorginho struggled to dictate play.
The Italian said: "Today Jorginho was in trouble and on the bench there wasn't a player for that position. I need an option for Jorginho."
Chelsea took the lead after nine minutes, through Pedro, but Newcastle responded and deservedly equalised five minutes before half-time through Ciaran Clark.
Sarri again bemoaned his side's mentality – a frequent complaint this season – for apparently being complacent after Pedro's opener.
The 60-year-old added: "After the goal I think we thought 'now it's easy', but it wasn't.
"We slept for 20, 25 minutes, so at the end of the first half we were in trouble. We need to improve in the mental reaction."
Eden Hazard again started as a 'false nine', with Olivier Giroud on the substitutes' bench and Alvaro Morata again left out, amid reports the Spain striker could leave.
Sarri, though, pointed to the importance of wingers, including Callum Hudson-Odoi – the 18-year-old who has been repeatedly linked with Bayern Munich – rather than the need for a striker.
Sarri added: "With Eden as a striker we need wingers. So we need Pedro. We need Odoi. We need Willian, of course."
Newcastle were watched by owner Mike Ashley for the first time since mid-November.
The Magpies had dropped into the bottom three prior to kick-off and stayed there, despite a spirited performance.
Boss Rafa Benitez hopes Ashley recognised the deficiencies of his side, which is in need of reinforcements.
"I think from the beginning of the season we know that we are close, but sometimes it's not enough," said Benitez, who said he would meet Ashley later on Saturday.
"Hopefully everybody can see the effort is there, we're trying our best and still it's not enough."
Benitez was asked if he was optimistic about incoming players.
He said: "Optimistic about the team, yes. Optimistic about other things... I don't talk about other things."
On falling into the drop zone, Benitez said: "We have to stay calm. It's a long distance race.
"Next week against Cardiff will be massive. Still, we have to win more games."
