The prospect of a New Zealand men's rowing eight at Lake Karapiro on November 2 at the world championships is closer to reality following the Kiwi squad's European campaign.

The two men's coxless four crews exceeded expectations, finishing second and fourth in the final of the World Cup in Lucerne.

Silver medallists David Eade, Jade Uru, Hamish Burson and Sean O'Neill finished 2.22 seconds behind the winners and world championship favourites Britain.

The fourth-placed crew of Ben Hammond, Chris Harris, Ian Seymour and Tyson Williams were 2.45s back.

Those results have reinforced the idea of an eight after the crews combined to make the final at the Henley Royal Regatta. They beat the British eight in the semifinal - that crew finished third in the final of two World Cups. The Kiwis then lost to the German crew who won those last two events.

Their success poses crucial questions for the selectors. Throwing most of their resources into an eight in the hope they might medal is a risk at such short notice.

But there is more prestige in winning a medal in the men's eight than any other event.

The selectors could also combine a useful four with that eight, but it probably wouldn't medal. Contrast that with the option of assembling their best, potentially medal-winning four and cobbling together an eight as an afterthought, so New Zealand is represented in the world championships' premier event.

The trials next month and the under-23 world championships in Belarus this weekend should provide further clarity.

The under-23 men's coxless four and double sculls performances will be monitored to see if there are athletes who could top up the senior men's eight, four or quadruple sculls boats.

Tinkering with the composition of the quad sculls is an option because versatile veterans such as Nathan Twaddle or Matthew Trott could move from sculling to the sweep oars of an eight or a four, if required. Athletes coming back from injury, such as Simon Watson and Michael Arms, could also be brought into the mix.

New Zealand Olympic Committee president Mike Stanley was the last man to stroke a world championship-winning eight for New Zealand in 1982 and 1983. He says the two coxless fours are a fine advertisement for the high-performance programme.

"They're consistent and have trained and raced in an environment with ferocious competition. There is certainly a swelling of talent in the men's heavyweight programme. Now it comes down to cutting and dicing the group correctly for the world championships.

"Obviously there are more than four rowers capable of taking the extra seats, so it [an eight] seems a logical solution."

Meanwhile, single sculler Emma Twigg is almost over the mysterious spell of fatigue which ended her campaign midway through the Henley regatta. The 23-year-old and her doctors still don't know what the problem was.

"It's been hard to pinpoint exactly what it was but I got to a point where I was lacking energy and sleeping most of the day. I had to make a call whether to push on, possibly doing more damage, or just have a break."

The former under-23 world champion had her best finish at a World Cup in Slovenia with a second place behind two-time Olympic champion Ekaterina Karsten of Belarus. The weariness kicked in soon after and she failed to make the World Cup final in Munich three weeks later.

"I discussed the situation with our manager Jan Taylor and the doctors. It came down to my call. I also talked with Dick [coach Tonks] and Alan [high performance manager Cotter]. We concluded there wasn't much point flogging me for the sake of it.

"Nothing like this has happened to me before. I've usually been good with injuries and recover with few setbacks so it was difficult to deal with mentally. The consolation was that I was in my best form but it was frustrating at the same time.

"Still, it has been the best time in the season to recuperate with the world championships over three months away."

During her recuperation Twigg enjoyed "the comforts of home" in Napier where Her mum Kerry's chicken soup was a highlight.

But that all finished last week when the squad reassembled for training ahead of further world championship trials. Twigg says she has been training but not quite at full capacity.