CREWE & Nantwich failed to maintain a powerful start as they slipped to a fourth consecutive defeat on Saturday.
Still struggling with a host of injuries, coach Nick Price had to make another six changes to the side that took to the field last week.
But his side settled quickly and shocked the confident hosts with strong running and aggressive forward play in the opening stages.
The big Oswestry forwards were driven off the ball and Crewe used the ball to great effect when they shipped it quickly down the backs.
With only five minutes on the clock, a strong run by Andre Zwijnen gave Tom Maguire, playing outside centre for the first time, room on the outside. He beat the last man and went over near the posts, before converting.
The home side hit back with a penalty and Crewe's lack of discipline at the ruck began to cost them again and again.
Price said: 'Every time we got ourselves into a scoring position, we gave away a silly penalty to give Oswestry the chance to clear their lines.'
On 19 minutes, a quickly-taken penalty caught Crewe off guard, allowing the Oswestry forwards to trundle over the line for an unconverted try.
They grabbed two tries and a conversion to make it 20-7 before the break, and despite surviving a lot of pressure from the South Cheshire outfit, kept the scoreline the same until the final whistle.
Crewe and Nantwich 2nds put Crewe and Nantwich 3rds in their place with an resounding 23-0 win on Saturday.
The victory kept the 2nds on track from promotion from the Miller Homes League Division Four South. The 3rds are in fifth.
Andrew Thompson, Karl Tatlock and Gav Wallace all got unconverted tries, and Simon Wall hit a penalty. A club spokesman said:
'Another keenly fought inter-club match showed the strength-in-depth at the club. In the end, greater experience and organisation proved to be the difference for the 2nds.'
* Crewe and Nantwich's Turf-a-Lotto scheme is still in full flow. Aimed at raising funds to improve facilities, five-metre square 'virtual plots' of land on the team's pitch at Crewe Vagrants are sold at £5 each.
Plot holders will be entered into an annual draw for three years, with the chance of winning up to £1,500 each time.
The draw is open to anyone. Tickets are available from Crewe Vagrants, or via e-mail at email@example.com