Testing for clues related to the Arc? This week is your chance, as Kalpana's important trials at Kempton commence

The horse racing season is heating up, with the Arc Trials taking centre stage. Here's a roundup of the key events and contenders to watch out for.

The September Stakes at Kempton, a Group 3 race on the Polytrack, is a significant trial for the Arc. This race offers an opportunity for horses to showcase their Longchamp claims, and this year's edition features Kalpana, who previously won this race in 2020 and used it as a stepping stone to success at Champions Day. Kalpana's main competition is expected to be Hong Kong Vase winner Giavellotto.

Meanwhile, in France, the Arc Trials day at Longchamp on Sunday will feature several Group 1 races in Britain, Ireland, and Germany. Notable contenders include Whirl, who may run in the Prix Vermeille before the Arc. Whirl, one of the single-figure price favorites for the Arc, will race against two of France's top Arc contenders, Aventure and Gezora. Aventure, having finished second in the previous year's Arc, has recently gained prominence as the new Arc market leader.

In the Prix Vermeille at Longchamp on Sunday, Aventure and Gezora will face off, along with other top contenders like the consistent Sosie, who finished fourth in last year's Arc and boasts a 5-6 record at Longchamp.

The Prix Foy will also see potential Arc candidates Los Angeles, Almaqam, and Byzantine Dream race alongside Sosie. Los Angeles, likely to start in the Prix Foy, is one of the contenders for the 2025 Arc, along with Whirl and Merchant, who is targeting the Prix Niel for an automatic Arc entry.

The Prix Niel is not without its own contenders, with Leffard, a colt trained by Jean Claude Rouget, being one to watch. The Grosser Preis von Baden, a key race in Germany, will also see the participation of Cold Heart, the sole Arc entry, and Alleno, trained by Marcel Weiss, who could be considered for a supplementary Arc entry if it wins the race.

Last year's Arc fourth Sosie has an impressive record at Longchamp, but other contenders like Delacroix, Shin Emperor, and White Birch, priced around 40-1, are also in the mix. Minnie Hauk and Tennessee Stud, who are among the 15 St Leger possibles, are entered in the Arc, but Minnie Hauk's participation at Doncaster seems unlikely.

Historically, races like the Irish Champion Stakes and the September Stakes at Kempton have seen previous Arc winners and contenders. For instance, Enable, a previous winner of the Arc, beat Crystal Ocean in the September Stakes in 2018 before justifying Arc favoritism on her next start. Similarly, Golden Horn was the last Irish Champion winner to follow up in the Arc in 2015, while Sottsass was beaten in the race in 2020 but landed Europe's most prestigious race on its next start.

Torquator Tasso's win in the Grosser Preis von Baden in 2021 was followed by an Arc victory, adding another chapter to the race's significance as a key trial for the Arc. As the Arc Trials continue, these races will provide valuable insights into the form of the horses vying for the coveted title.