Catherina McKiernan will arrive in Lisbon this afternoon, to discover at least one item of good news as she attempts to vindicate a growing reputation as one of the best road runners in the world, here tomorrow.

The Kenyan Tegla Lorupe has proved unbeatable in each of the last four runnings of the Lisbon half-marathon, so much so, that almost by definition, her opposition was competing for second place.

Now she is unavailable and the effect will be to generate new hope in everybody else for this, the first major event of the road-racing season. In every other respect, however, it remains an authentic test for the London Marathon in six weeks' time.

Lorupe's compatriot, Joyce Chepchumba, winner of last year's London Marathon, is here. So, too, is the woman she overtook in the last few strides to win that race, Liz McColgan, and with Yuka Hata of Japan, Sonja Krolik Oberem (Germany) and the two Romanians, Cristina Pomacu and Alina Tecuta also chasing the prize money, the quality of the entry is unquestioned.

For McKiernan, reborn in a remarkable sequence of successes which has produced 11 wins of varying merit and meaning in the last nine months, it is the most demanding challenge yet in this new facet of a fine career.

Forced to run in the slipstream of Sonia O'Sullivan for so long, the Cavan runner is now an international celebrity in her own right. Her absence from the World Cross Country Championships in Marrakesh in eight days' time, is interpreted by IAAF officials as devaluing the longer of the two races. McKiernan, four times runnerup in the world championship, still hankers for the chance to redress that situation and has already targeted next year's championship in Belfast as the occasion when monumental persistence will, at last, be rewarded.

Many believe that road running may yet yield the success which has so far eluded her in cross country competition and to that extent, her performance here against many proven athletes will be revealing, not just in the context of the London Marathon, but beyond that, the European Marathon Championship in Budapest in August.

By any standard, hers has been a spectacularly successful record since winning the Dublin mini-marathon in June. And the high point came in Berlin in September when her time of two hours 23 minutes 44 seconds, the sixth-fastest in history by a woman, was seen as astonishing for a marathon debutante.

Within the sport, McKiernan is known as an athlete who understates her own achievements, but having covered the last five kilometres in just over 16 minutes in Berlin, she believes that she can improve significantly on her time in London.

"Because I'd never run a marathon before, I was too conservative at the start and only really pushed it in the closing stages. With that experience to work on, I should be faster in my next race, but logic, I'm afraid, doesn't always hold up in athletics."

McKiernan says her move to Dublin has been a significant factor in her recent success. "Now, I have no shortage of company in training and that's brought back a lot of the old enjoyment."

The other, perhaps, more pertinent reason for her steady rate of progression has been the absence of injury worries.

Tomorrow's race will be an open one, accommodating both men and women, and to win her section, McKiernan may have to reproduce the verve and self-belief which enabled her to put almost 300 metres between herself and the pack in Dunleer five weeks ago.

The weather promises to be ideal for tomorrow's race, but McKiernan will be forced to concede the advantages in topography to McColgan, who has twice finished third in the race in recent years. The resilient Scot is again in good form, as evidenced by a couple of impressive runs in America where she is doing her homework for the London Marathon. Significantly, however, her record against McKiernan is not a good one - and that could prove important.

Chepchumba didn't run particularly well in the international cross country race in Belfast in January, but, as a specialist road runner, her challenge is likely to be a lot more imposing here.

In the absence of Albertina Dias, Aurora Cunha will head up Portugal's hopes of winning the race for the first time, but the bigger threat to McKiernan may emanate from Cristina Pomacu, who was second to Lorupe two years ago.

Kenyan runners, led by Joseph Kimani and John Kagwe, dominate the entry for the men's race in which Irish interest will focus on the progress of Noel Berkeley.

It is perhaps, a measure of the thirst for change that the women's event is attracting much of the media attention. If McKiernan can make it big here tomorrow, it may yet mark a significant milestone on her journey to international fulfilment.