Adam Reed scored in the eighth minute of injury time as unbeaten Burton continued their bright start to the campaign.
It was agony for Stanley as James Gray hit the inside of the post after 83 minutes and the ball bounced out only for visiting goalkeeper Dean Lyness to spectacularly keep out Kal Naismith's follow up.
The hosts had other chances while Reds keeper Marcus Bettinelli, on loan from Fulham, was also in top form, keeping out long-range shots from Michael Symes and Adam McGurk and a volley from Rene Howe. He also tipped over another Howe effort late on.
"The 97th minute is a great time to score for us as there is no way back for them," said Summerfield.
"We played well in patches and probably deserved the win but, in the final 20 minutes, they could have won the game as well.
"We did not really threaten their goal and couldn't break through but thankfully we finally got the win.
"Adam (Reed) has been patient and waited for his chance but he came in on Saturday, took it and has staked a claim for the shirt."
The lengthy of injury time was following a clash of heads between Stanley's Michael Liddle and Burton's Jimmy Phillips.
Phillips was treated pitch-side and went back on. However he sat down in the centre circle five minutes from time and had to be carried off the pitch on a stretcher and went to the local hospital.
"We are waiting for news," added Summerfield. "Our fitness coach felt he was well enough to carry on and he knew what he was doing but now we will monitor him."
- Sports & Recreation
- Kal Naismith
- Rene Howe
- Michael Symes
- Adam McGurk