IT'S make or break tomorrow for British women (two of them Scots) with Olympic modern pentathlon aspirations.

The world championships in Rome, the final qualification event, will effectively decide who competes in London 2012.

Britain enjoys a remarkable embarrassment of riches in this five-sport discipline: five women among the top 25 in the current world rankings, headed by fifth-placed Mhairi Spence from Farr, near Inverness. The reigning Olympic silver medallist, Heather Fell, is ninth, and the quintet includes Freyja Prentice from Inverurie, 25th.

Four of the five (Spence, Fell, Samantha Murray and Prentice) contest the world semi-finals tomorrow, attempting to qualify for Saturday's final. The fifth of the quintet, Katy Burke, led a three-strong GB team to bronze in the world relay final on Monday. This trio included two Brits from outside the world top 25, telling much about UK depth.

Britain had two in the world top 10 last year and four in 16, and boasts four of the nine available Olympic medals since the women's event was added in 2000. Yet while three athletes per nation can qualify in every athletics discipline – a quota sure to come under threat as more sports press for inclusion – only two per nation can be selected in modern pentathlon.

Prentice, 22 and 2010 world junior silver medallist, was hampered by injury over the winter but has now recovered. She is the only UK woman actually qualified for the Olympics, but eighth at last year's European Championships does not guarantee selection. Nor would a medal in Rome, despite it being the surest marker of current form. Thereafter athletes are dependent on world rankings, and more points can only be gained at the World Cup final, in China at the end of the month. Selection will be made early in June.

Girvan-born Stephanie Cook, who won Olympic gold in 2000, reckons the pressure of the Rome event is greater, even, than the Olympics"because of the level of competition just to qualify".

This intensity is not peculiar to modern pentathlon, however. Witness track cycling where Sir Chris Hoy is up against the reigning Olympic sprint and keirin silver medallists (GB team-mates Jason Kenney and Ross Edgar) who he beat in Beijing. They are challenging his right to defend in London because track cycling representation has been cut from two per nation to just one.

Likewise in sailing, where only one boat per class is allowed. When Scotland's 470 helmsman Luke Patience and crewman Stuart Bithell were selected a few weeks ago it left Nick Rogers and Chris Grube and Nick Asher and Elliot Willis on the beach. Rogers won silver in Athens and Beijing, while Asher and Willis have twice won world titles.

And when triple Olympic champion Ben Aislie was chosen for the Finn, it scuppered the hopes of world champion Ed Wright and European champion Giles Scott. If it were three-per-event like athletics, Britain would have been candidates to sweep the podium.

In combat sports, an athlete in continental or world championships can only qualify a representative from his country in a given weight class, but still must win the domestic selection battle at that weight. This led to Beijing Olympian Khalid Yafai, the world No.4 at 52kg, recently being ousted in a box-off by Andrew Selby.

Such examples over the years have prompted suggestions that the IOC permit wild cards. Athletics allows champions to defend automatically at their world championships. One NBC columnist has recently been promoting the notion at the Olympics – well they would; it might relieve their grindingly parochial coverage.

Even the IOC got in on the act, notably, in 1988. Seb Coe succumbed to a respiratory infection and failed to qualify to defend the 1500m title he had won twice.

Peter Elliott, Steve Cram, and Steve Crabb had qualified legitimately, but no less than IOC president Samaranch appealed to GB selectors to pick Coe, saying he was "a very special athlete", and suggested he be given a wild card. He quickly had to back down, realising this was counter to the Olympic charter.

Rightly in my view, there has been no attempt to revive the proposal. Doubtless fans and many among the media would love the resultant nostalgia of former champions. It's all very well for the Masters to wheel out geriatrics past their sell-by date, but the Olympics should remain above that. It is just about acceptable for single wild cards for developing nations in athletics and swimming. The Olympics are, as the movement's founder said, "for the whole world".

Yet they are not a platform solely for the best. Kenya has an embarrassment of middle distance and endurance riches. They have omitted world marathon record holder Patrick Makau (2:03.38 in Berlin last September) from their Olympic team, picking Virgin London marathon winner Wilson Kipsang, two-time world champion Abel Kirui, and Moses Mosop, who was third in Rotterdam. All but one of the top 35 marathon runners this year are Kenyan or Ethiopian. Of 419 men worldwide last year who were inside the 2:15 Olympic marathon standard, 278 were Kenyan. All of the top 20 were Kenyan (slowest 2:06.31). Eight of the best 11 steeplechasers last year were Kenyan, eight out of 20 at 1500m (including the top four), 13 of the top 20 at 10k. Similarly, 20 of the fastest 28 100m sprinters this year are either Jamaican or American.

Are we to accept them and exclude other nations? The Olympics would be much duller and elitist – a devalued spectacle – if a deck of wild cards were dealt.