Enyimba went down to a disappointing 1-0 home defeat to Ikorodu City in a matchday 13 fixture in Aba on Sunday.
Tomisin Adebayo scored the decisive goal 20 minutes from time.
Defending champions Rangers held their hosts Niger Tornadoes to a 1-1 draw at the Bako Kontagora Stadium, Minna.
John Zakka gave Tornadoes the lead in the 25th minute, while Waheed Adebayo restored parity for Rangers 15 minutes from time.
In Ilorin, Kwara United and Rivers United battled to a 1-1 draw.
Emmanuel Ekpeyong headed Kwara United in front in the 71st minute, while Wasiu Falolu levelled for the visitors one minute later.
Full Results
Kwara Utd 1-1 Rivers Utd
Tornadoes 1-1 Rangers
Inter Lagos 2-1 Abia Warriors
Enyimba 0-1 Ikorodu City
Katsina Utd 2-1 Nasarawa Utd
Wolves 2-1 Sporting Lagos
NPFL: Ikorodu City upset Enyimba, Rangers, Rivers United slip up