Inter Milan coach Antonio Conte has challenged Romelu Lukaku to produce more performances like the two-goal showing that helped his side to a 3-1 home win over Lazio in Serie A on Sunday.
AC Milan's surprise defeat at Spezia on Saturday opened the door for Inter to leapfrog their rivals into top spot, which they did thanks to Lukaku's double and a Lautaro Martinez goal.
Conte highlighted Belgium striker Lukaku's contribution, as the 27-year-old took his league goal tally to 16 for the season, calling for more of the same in the coming weeks.
"It is important for Romelu to give these answers," Conte said. "There are times when there is lower performance from him. We need this Romelu and this team performance."
Inter have trailed Milan for much of the season, with the pair meeting in next weekend's mouth-watering Milan derby at the San Siro.
But having finally climbed to the summit, Conte has urged his side to make sure they stay there.
"Going to the top was a goal, we've been chasing for some time," he added. "We achieved it today, against an excellent team.
"We have shown mental strength and we are doing it with a certain continuity. I am very happy, but this must be a starting point. We still have a lot of work to do."
Lazio were the better team for long spells of Sunday's match at San Siro, with Inter's opener, from the penalty spot, coming somewhat against the run of play.
Lazio's Wesley Hoedt was penalised for fouling Martinez, a decision visiting coach Simone Inzaghi was unhappy with.
"I would have liked to have seen the referee review the decision with the VAR," he said. "I am not sure why he didn't. The penalty changed the game, we were dominating."