England 272 all out (50 overs) beat Namibia 217-9 (50 overs) by 55 runs.
England finally beat minnows Namibia but it was a hard-earned victory in Port Elizabeth.
England thought the 272 they had scored after being put into bat on a slow pitch would be enough to beat the amateurs and claim a valuable four points.
But at one stage it looked as though a huge upset was on the cards when 21-year-old student Jan-Berry Burger was smashing the England bowlers around the ground.
He was eventually out for 85, off just 86 balls, which was the first time a Namibian had scored a fifty in a one-day international.
However, the remaining batsmen could not hit the runs required and the game petered out.
Questions will be asked of England's inability to bowl out so-called lesser opposition.
They failed to dismiss Holland on Sunday and could not get rid of Namibia on Wednesday.
England toiled with the ball on occasions and will have to improve if they are to beat Pakistan in the next game.
England suffered a setback even before the match had started when captain Nasser Hussain was ruled out with a stiff neck.
Up stepped Alec Stewart, who had relinquished the England captaincy four years ago after a poor World Cup, to take the reins once more.
And he played well for his 60, his 28th one-day international fifty, but was furious when he failed to get behind a shot and was caught on the boundary.
Burger was a delight to watch
Nick Knight (8) was the first man out when his attempted pull shot was caught by Louis Burger off Rudie van Vuuren.
Then Michael Vaughan (14) followed him back to the pavilion with a copy-cat shot.
Trescothick, with a new batting stance, hit 58 off 66 balls and with Stewart steadied the ship.
Paul Collingwood and Andrew Flintoff also got themselves in before playing horrendous shots.
Craig White was incredibly lucky to stay at the crease when he survived a run-out and finally went for 35.
Ian Blackwell thought he was out too when a spliced shot was caught.
But the umpire signalled a no-ball because the required number of fielders was not in the circle.
He was definitely out an over later when he was caught behind. And he was unable to bowl after tweaking his back while fielding.
White, Ronnie Irani and Andrew Caddick were all out in the final over as Van Vuuren took five wickets in the match, the first Namibian ever to do so.
Van Vuuren enjoyed a cameo appearance with the bat too, smashing Jimmy Anderson for six with the final ball.