Two more set-pieces in each half put United on the way to a third successive Zamaretto League defeat with Leamington taking all premier division three points in Saturday's 2-1 success at Spencer Stadium.
Jeffrey watched a video of the game and fum
ed: "Watching it again was worse than seeing it the first time! It's up to me to put it right because our defending at set-pieces is costing us.
"We did more than enough to have got something from the game because we matched Leamington in open play but we knew they would be dangerous at set-pieces.
"We are becoming a soft tough at corners and free-kicks. The players have got to learn to be touch-tight at corners and I'm sure we can put it right.
"We had a good session this week on set-pieces but the players will face a real challenge in this area at Bashley, they are the most direct team in the division."
But Jeffrey was pleased with the way Mark Scott performed on his debut, taking over from Joe Murrell, after being signed on a month's loan from Swindon Town.
"Mark (Scott) hasn't played for a while so he was a bit rusty but he's training with the Swindon first team squad and we've got him at the right time with Joe (Murrell) being suspended for Saturday and unavailable midweek because of his studies," added Jeffrey.
The United boss is hoping skipper Nathan Haisley will be fit for the trip to Bashley after a bruised toe kept him out of the Leamington game. Following the trip to Bashley, United are at home to Didcot Town on Tuesday.
- Read up on United in this week's Banbury Guardian
