Tomas Soucek was the only survivor of a drastic rotation exercise and prevented any post-match scrutiny on his manager.
David Moyes’ decision to make ten changes from the team which suffered defeat at Liverpool appeared a risky gamble until Soucek’s winner 20 minutes from time.
With West Ham’s third successive European campaign already underway, Moyes is preparing for a chaotic season and stars including Jarrod Bowen, James Ward-Prowse and Lucas Paqueta were all left at home.
His revamped team endured a frequently uncomfortable evening against Lincoln, 13th in League One, until Soucek’s scruffy winner cheered the 1,836 travelling supporters.
Moyes has greater strength in depth than ever before and can afford to take these risks, while still fielding virtually a full starting XI of internationals.
Lincoln had already defeated Premier League opposition this season after beating Sheffield United on penalties in the previous round, and they were in control for long periods of the first-half.
Alex Mitchell, the defender, converted from close range but was flagged offside, while West Ham’s goalkeeper Lukasz Fabianski produced a fine save to deny Reeco Hackett-Fairchild shortly before half-time.
With West Ham struggling for fluency, the fans were demanding the introduction of teenage forward Divin Mubama.
When Mubama and Edson Alvarez were brought on in the 66th minute, they produced an instant response.
Soucek then bundled in Said Benrahma’s corner at the near post to claim the victory, while West Ham could have won more comfortably with Ben Johnson striking the post.
Lincoln did have a late chance to force penalties but substitute Dylan Duffy’s shot was pushed away by a diving Fabianski.