Radi Majewski's goal settled the game at Sincil Bank with attention turning straight away to next weekend's Championship opener against Barnsley at the City Ground.
Steve McClaren will hope to have added to his three new signings by the time he makes his competitive return to English football.
‘I will be nervous when we face Barnsley on Saturday. I always am. It’s going into the unknown as well,” said the City Ground boss, quoted in the Daily Mail.
Barnsley have recorded comfortable pre-season wins over the likes of Hartlepool, Sheffield Wednesday and Scunthorpe, putting five goals past the latter at Glanford Park on Saturday.