Hazard has praised Chelsea and says they have what it takes to overcome any test that comes their way after a 3-1 away win against Bournemouth.
Tottenham beat Watford earlier in the day 4-0 to reduce the deficit separating them from Chelsea to four points. But the win over Bournemouth restored the seven-point lead.
Costa’s deflected off Adam Smith to open the scoring, before a moment of brilliance from Hazard doubled the lead. Joshua King pulled one back before the break.
But the table toppers were back in the game after Marcos Alonso scored his fifth goal of the season from a free kick.
“We passed the test,” Hazard told BT Sport. “We knew the result of Tottenham before the game, so the only thing [they could do] to stay at seven points was to win. We scored three good goals and we deserved to win.
“It’s easier to control the game when you score first. At the end of the first half, we were a little bit down. They scored one goal, but after half-time we did well and controlled the game. We are happy.
“We have to believe. This is one step closer to the title. We have seven games to play and we are ready for the seven games.”