Mark Cooper's pre-season excitement vanished after watching Tamworth tumble to defeat against Conference newcomers Weymouth.
Weymouth, who are back in the top flight of non-League after a 17-year absence, eased to a 3-1 victory at The Lamb.
"It is the most let-down I have ever felt after a game," said shellshocked Lambs manager Cooper.
"We made it easy for them to win by not doing what we had practised. We have worked on set-pieces through the pre-season but that was our downfall. I feel let down by my players."
Tamworth had been unbeaten in their pre-season matches but it only took ten seconds for the Nationwide South champions to open the scoring.
The Lambs failed to deal with a simple clearance and former Shrewsbury Town and Hereford United midfielder Ben Smith chipped the ball over Sean Bowles.
Some more poor defending was to blame when Ashley Vickers headed home 14 minutes later from El Kholti's corner while Simon Downer added a close-range third five minutes into the second period, before Lambs substitute Matt Williams salvaged some pride for the home side four minutes from time.
Aaron Webster notched Burton Albion's winner as they ended their More-cambe jinx with a 1-0 victory at Christie Park.
Webster's 77th-minute penalty, awarded after Ged Brannan handled Gary Rowett's cross, earned victory over the Seasiders after eight successive Conference defeats to the Lancashire club.
Stafford Rangers also netted from the penalty spot as they marked their first Conference match in 11 years with a 1-1 draw at Grays Athletic.
Rangers, promoted through the Nationwide North play-offs, trailed to Michael Kightly's sixth-minute effort but Neil Grayson converted a spot-kick three minutes later after Ged Murphy had been dragged down.