Search is on for a true team player: The three finalists for the Scottish International Piano Competition this year face an additional and novel test

But there's a further test to face before that: a brand new dimension to the competition final, which is played out tonight at the Royal Scottish Academy of Music and Drama (RSAMD). For the first time ever in the SIPC, all three finalists will have to prove their abilities as team players in a chamber music scenario. Having spent yesterday rehearsing with the Brodsky Quartet, each will now set out to prove tonight that there is more to their pianism than going it alone.

This is a very deliberate move by the competition organisers to seek a much more rounded musicianship from its competitors - away from the solitary prima donna display to one that demonstrates greater maturity, sophistication and insight - and a decision that was significantly influenced by one of this year's international judging panel, the Edinburgh-born pianist Susan Tomes.

"When I was last on the jury, in 2007, I made an impassioned speech to the board members that the chamber music aspect be included," says Tomes, who not only feels that it helps give the SIPC a different flavour from other international competitions, but that it is an essential part of the armoury for most pianists trying to make it in today's difficult musical world.

"Pianists today have to be more broadly based. Yes, there are remarkable individuals who just want to go it alone and they do that very well. But for many more it is necessary to be active in the musical community in so many different ways. Many make the mistake of thinking that chamber repertoire demands less skill than the solo repertoire. I'm often struck how left out they are."

Tomes is fully qualified to say so. As one of the UK's leading chamber musicians, she has performed extensively both as solo recitalist and collaborator, the latter predominantly as a founder member of two chamber ensembles, Domus and the Florestan trio.We don't see so much of her up here in Scotland as a performer - though look out for her in Perth next year when she embarks on a series of Mozart piano and violin sonatas with the violinist Erich Hobart of the Quatuor Mosaque - but many will have encountered her writings on music, either in her regular newspaper columns or in her two very readable books, Beyond the Notes and Out of Silence - A Pianist's Yearbook.

In the latter of these, published only a few months ago, in which she colourfully explores music's place in the wider world, Tomes uses her own experiences of tennis to capture the fundamental distinction between how the chamber musician and the soloist operate.

"It seemed to me that there was equal skill in hitting the ball so that the other person 'could' hit it back," she writes. "It struck me that deliberately hitting the ball out of the other person's reach was very unsportsmanlike. When I tell Bob (her husband] this, he's very amused and says, 'There speaks a true chamber musician.'"

In music though, says Tomes, it is perfectly possible to combine the killer instinct with the team player. "Many of the greatest solo pianists did it - Cortot, Rubenstein and Serkin among them," she argues. The whole point of tonight's new addition to the competition is to test that versatility. But what exactly will Tomes and her fellow judges be looking for?

"I'm guessing we'll be looking for a whole range of things: the ability to listen and respond; the ability to lead; and the ability to dip in and out, adding their own sound, their own thoughts to the whole quartet," she says.

"Some competitors may find that difficult and simply set a volume level for themselves and deliver it regardless of all that's happening around them. That would be disappointing. I'd like to see them get something out of the music that is more than merely the sum of its parts."

And that goes for the whole jigsaw of trials and tribulations that make up this week's fascinating circus of pianism and musicianship, of which the chamber music element is but one component. Once again, competitors have had to learn a specially-commissioned test piece - written by another of the jurors, Thea Musgrave, but this year given to the competitors with absolutely no tempo or dynamic markings, or even a title, to make of it what they will.

There have been a series of masterclasses by members of the jury, including one by Tomes herself. And a new stipulation was introduced asking competitors to include a single major work of not less than 25 minutes as part of their 50-minute Stage Two recital.

The changes had an interesting impact on the nature of entrant, according to Robert Love, the former head of drama at STV who is now a prominent member of the competition's organising committee."Where we would normally have expected 40 pianists at the start, we only had 28 this year, and the majority of them turned out to be at the higher-than-usual end of the age spectrum, which we think is as a result of requirements that were much more stringent," he says.

So it all hots up from tonight, when the final three candidates - Pavel Kolesnikov , Nadezda Pisareva and Oxana Shevchenko - hope to show Tomes and her juror colleagues how musically complete they are. The solo limelight on Sunday is one thing, and will be as glamorous as an Oscar ceremony, but the more intimate testing ground of the chamber ensemble will be as true a test of character.

•Scottish International Piano Competition Finals: Chamber Music Performances with the Brodsky Quartet, RSAMD, tonight; Concerto Final with the BBC SSO, City Halls, Glasgow, 19 September

• Other events include recitals by Victoria Postnikova, RSAMD, 17 September and Idil Biret, RSAMD, 18 September. For more information, visit www.sipc2010.org