Despite being beaten from range by England international Ashley Young, Lewis was pleased with his overall performance.
"Ashley Young is a fantastic player and if you let him shoot from the edge of the box he can do that," he said.
"But I'll look at the video and see if there was anything else I could have done about it."
Trialist Franck Queudrue played the final 30 minutes of the match and is set for talks with boss Gary Johnson, but Liam Chilvers was left out of the squad and will not be offered terms.
It's probably a good thing that we've made a few mistakes because it gives us a chance to sharpen up
Peterborough goalkeeper Joe Lewis
Posh have won just once in four pre-season matches, but Lewis believes progress is being made.
"It's probably a good thing that we've made a few mistakes because it gives us a chance to sharpen up," he said.
A reserve side will travel to Gillingham on Tuesday night with former Bristol City man Steve Collis set to line-up in goal.
The 29-year-old worked with Johnson at Ashton Gate and will provide cover for James McKeown who is training at Barrow with a view to a loan move.
Bookmark with:
What are these?