The Serie A title race took another turn on Saturday as Inter Milan beat Genoa 3-0 to move second in the table.
The win means that the Antonio Conte men are just four points behind leaders Juventus with two games to spare.
Lukaku opened the scoring in the 34th minute with a header from a Cristiano Biraghi cross, before Sanchez struck in the 83rd minute, and Lukaku added his second in stoppage time.
Genoa remains fourth from bottom, four points above the relegation zone having played a game more than Lecce, their rivals for the final relegation place.
Juve will win the league with two games to spare if they beat Sampdoria on Sunday, but have only won once in their past five games.
In another game of the day, Sassuolo had four goals disallowed for offside by VAR in their 2-0 loss away at Napoli.
Elseid Hysaj put the hosts in front after eight minutes but then Sassuolo then had four strikes they believed to be legitimate goals taken away by the video technology.
Three out of the four offside calls were not spotted by referee Gianluca Aureliano nor his linesmen, with Napoli midfielder Allan putting the game beyond the visitors in second-half stoppage time.
Serie A Saturday results
Brescia 1-2 ParmaGenoa 0-3 Inter MilanNapoli 2-0 Sassuolo