Pete Steindl, the Scotland coach, last night made no excuses for his side's latest hammering by Afghanistan.

Steindl's men were on the receiving end of some debatable decisions as they suffered a seven-wicket loss in the first of two World League Championship encounters – they double as qualifiers for the World Cup – with the Afghans in Sharjah.

The dismissal of Richie Berrington, controversially given out caught behind, was a bone of contention – the Sri Lankan umpire was reported to have apologised for the error after the match – but Steindl chose only to assess his own team's performance, and it was damning.

"We simply weren't good enough today," he said. "We made a decent start but we lost our way in the middle overs when we lost a clutch of wickets. There was a bit of a recovery but our total was nowhere close to being a challenging one."

It is doubtful whether a reprieve for Berrington would have had an influence on the outcome, but the Greenock man, having established himself and reached a half-century, was well placed to launch an attack during the last 15 overs of Scotland's innings. Instead, his departure sparked a mid-innings collapse and the Scots, who had their sights on a 250 total, had to settle for 199 for eight, thus relieving a lot of pressure from the Afghans.

Berrington looked stunned when umpire Ruchira Palliyaguruge raised a finger to give him out and Craig Wright, the former Saltires captain, commentating on an internet broadcast, said: "It looked like a bad decision to me; the ball clearly brushed Richie's pad."

A Scotland source said: "The umpire apologised for the decision at the end of the match. He went up to Gordon Drummond [the captain] and admitted he got it wrong. "

As it turned out, a century from Nawroz Mangal allowed the Afghans to cruise to their target with seven wickets, and more than 16 overs, to spare.

Mangal watched from the other end as Mo Shahzad, so often the hammer of the Scots, got his side off to a flier. Shahzad faced just 11 balls for his 19 but the Saltires fought back to take three quick wickets.

Iain Wardlaw claimed his first ODI scalp when Shahzad gloved one to David Murphy and the bowler followed up by dismissing Asghar Stanikzai. Majid Haq then equalled John Blain's record of wickets in one-day internationals when he trapped Rahmat Shah in front.

Having reduced their rivals to 59 for three, Scotland must have felt they were firmly in contention: Mangal had other ideas, launching a ferocious counterattack which took the game away from them. None of the bowlers were spared as Mangal delighted the boisterous Afghanistan supporters by bludgeoning the ball to all corners of the ground.

Preston Mommsen came in for particularly heavy punishment, the Carlton spinner being hit for three 6s in his one over which cost 25 runs.

Mangal accelerated to his first ODI century from just 86 deliveries, with six 4s and six 6s. He hit two more boun-daries but allowed his partner Sami Shenwari enough of the strike to reach 55 not out in an unbeaten stand of 144.

It had looked promising earlier in the day when Scotland, sent in to bat, refused to be dictated to by the dangerous Hamid Hassan. Kyle Coetzer, in particular, took the initiative with three boun-daries and a 6 off Hassan in his 23. His departure, quickly followed by that of Calum MacLeod, left Matt Machan and Richie Berrington to rebuild the innings. They had done the hard work in adding 99 when the batting power-play sparked a collapse.

Machan was first to go when he got the thinnest of edges to be caught behind off Dawlat Zadran. He was followed – controversially – by Berring-ton, whose 51 included four 4s and the Scots, poised to go on the offensive at 133 for two, collapsed to 149 for seven.

A hard-hitting 21 from Drummond and Moneeb Iqbal's 26 not out carried them to 199 but it proved woefully inadequate once Mangal went to work on an increasingly wayward bowling attack.

The sides meet again tomorrow when Scotland must gain revenge to stay ahead of Afghanistan in the eight-team table from which two will automatically qualify for the 2015 World Cup.