PETE Trego believes Somerset are the best one-day team in the country, but admitted they have to prove it by winning the Clydesdale Bank 40.

Trego's career-best 147 took Somerset to a 249-run win over Glamorgan and earned them a home semi-final against Essex this Saturday.

Somerset have finished second in the last three domestic one-day competitions – including the Twenty20 final last month – and are desperate to go one better.

Trego said: "Every time we come second, it spurs us on and I have no doubt that when we crack that win then a string of wins will follow.

"We are probably the best one-day side in the country and I think that is pretty fair to say, but it is all about seeing it through and having the nerve on the day.

"We have got a big semi-final first before we think about winning the competition."

Teenager Jos Buttler scored 90 not out as Somerset set two new 40-over records – their highest total (368-4) and their greatest victory margin.

However, skipper Marcus Trescothick knows highly-motivated Essex will pose a much tougher test.

"When you get to the last four, it depends how you play on the day," he said. "Regardless of who you play, you will have to perform to your best."

Somerset will have to win the CB40 without Zander de Bruyn. The South African has been allowed to return home early to play for the Lions in the Champions League.

Trescothick said: "The experience he has given us has been great. He has performed in all formats and he is a three-dimensional player.

"He has a big challenge ahead. We are pretty keen as a club to move forward and get players in the IPL and the Champions League."

Somerset will have Craig Kieswetter back after England Twenty20 duty. He misses the first day of their final home Championship match against Lancashire tomorrow because of the second T20 international.

But he will then be substituted back into the side and a previously-nominated player will drop out.