Should you back or avoid these four favourites in the big races at Doncaster and Leopardstown on Saturday?

We assess the chances of four favourites at Doncaster and Leopardstown on Saturday to determine whether you should back or avoid them at the current prices . . .

Porta Fortuna

Race: Coolmore America 'Justify' Matron Stakes (2.50 Leopardstown)

Odds: 11-10

Porta Fortuna comes into this with an incredibly consistent profile, having failed to finish out of the first three in her ten career starts.

Donnacha O'Brien's filly was beaten by just a neck when second in the 1,000 Guineas at Newmarket on her three-year-old debut and has won both starts since, following her Coronation Stakes success with a three-and-three-quarter-length win in the Falmouth Stakes at Newmarket's July meeting last time.

Jabaara (yellow): chased home Porta Fortuna in the Falmouth Stakes at Newmarket this month

Porta Fortuna: winner of the Falmouth StakesCredit: Alan Crowhurst

The Falmouth win brought her Group 1 tally to three, and on form she is very much the one to beat.

Verdict: Back

Porta Fortuna14:50 Leopardstown

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Jky: Tnr: Donnacha Aidan O'Brien

Kinross

Race: Betfred Park Stakes (3.00 Doncaster)

Odds: 5-2

Kinross began this season with a respectable second in the Chipchase Stakes at Newcastle and that form has worked out well with the winner, Montassib, landing the Group 1 Sprint Cup at Haydock last weekend.

Ralph Beckett's seven-year-old has not managed to run up to that level in two subsequent outings, finishing down the field in the July Cup before a third in the Lennox Stakes at Glorious Goodwood.

Audience: easy winner of the Lennox Stakes

Kinross (left): finished third in the Lennox Stakes behind AudienceCredit: Edward Whitaker

The Lennox run brought his form figures over 7f to an impressive 189114321111123 (8-15), but he has looked a little below his best this season and faces some improving rivals here in Lead Artist, Lake Forest and Al Shabab Storm. At the prices, he rates as one to oppose.

Verdict: Avoid

Kinross15:00 Doncaster

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Jky: Rossa Ryan Tnr: Ralph Beckett

Economics

Race: Royal Bahrain Irish Champion Stakes (3.25 Leopardstown)

Odds: 11-10

The William Haggas-trained Economics is yet to taste defeat this season, following up a Newbury maiden success with a six-length victory in the Dante at York and a cosy win in last month's Prix Guillaume d'Ornano at Deauville.

He retains significant scope for improvement on the back of just four runs and this track should suit him.

Economics (Tom Marquand) wins the Dante at York

Economics: wins the Dante at York under Tom MarquandCredit: Edward Whitaker

However, this represents a first start in Group 1 company and a first run against his elders, a group which includes six-time top-level winner Auguste Rodin. The price difference between those two looks too big, while on Racing Post Ratings both Los Angeles and Ghostwriter are closely matched with Economics and warrant respect.

Verdict: Avoid

Economics15:25 Leopardstown

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Jky: Tnr: William Haggas

Illinois

Race: Betfred St Leger Stakes (3.40 Doncaster)

Odds: 7-4

Illinois has won twice in his seven-race career, most recently in the 1m6f Group 2 Queen's Vase at Royal Ascot.

Aidan O'Brien's colt has finished second dropped to 1m4f in two subsequent runs, firstly when two lengths behind Sosie in the Grand Prix de Paris and then when a neck behind Los Angeles in last month's Great Voltigeur Stakes. On the evidence of those runs, stepping back up in trip in Saturday's 1m6½f St Leger will be a plus.

Los Angeles (Ryan Moore, second from right) wins the Great Voltigeur

Illinois (second left): second behind Los Angeles at YorkCredit: Edward Whitaker

The same should apply to his stablemate Jan Brueghel and the David Menuisier-trained Sunway, however, and opposing him with the former looks the value call.

Verdict: Avoid