Wallingford forwards coach Simon Henderson says their confidence has grown as the season has gone on.
The south Oxfordshire club lie second in Southern Counties North, six points ahead of third-placed Buckingham, so look odds-on for a play-off spot.
Now their sights are set on reeling in leaders Olney, who visit the Hithercroft on Saturday.
Henderson said: "At the beginning of the season we didn't believe in ourselves.
"But now we have played every team once and know we can beat them.
"Promotion is in our hands now and to win the league Olney have to slip up a couple of times, but you never know.
"Our fixtures are quite good after Olney this weekend.
"It shows our strength that our second team are top of their league as well."
Coach Chris Norrington added: "Saturday was the first time Wallingford have won at Witney in my recollection.
"We are making a lot of history this year. Whatever happens we have got a lot to be proud of.
"We now just want to prove we can beat the team on top in the league, Olney."
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