It's a bad day for Timo Glock, and Marussia, as it has been confirmed that the German driver will have to miss the race in Valencia as he has a serious stomach bug. His appearance over the weekend had been in doubt after limited participation in the practice sessions, and sitting out qualifying altogether, but we had hoped he'd be feeling better for the race. The FIA stewards had said he would be allowed to race despite not qualifying, if he was feeling better, but it was not to be.

The team issued a statement to confirm the news, along with wishing Timo a speedy recovery, and they've also thanked fans for all the good wishes to both Glock and Charles Pic - who will race on alone this afternoon.

Timo received medical guidance yesterday afternoon and his symptoms suggest that he is suffering from an intestinal infection. He has been advised that it would be unwise for him to race given the severity of the complaint and that he should focus instead on recuperating.

Timo spent the evening resting at his hotel in Valencia and is in good spirits. He will return home later today.

- Marussia statement

The unfortunate timing of Glock's illness has made some F1 followers start thinking about the reserve driver situation. Marussia signed María de Villota as test driver earlier this year, but she's nowhere near ready to join in a race weekend. At the time the deal was announced they said she would be able to "sample some F1 machinery later in the year." They certainly didn't mean throwing her in at the deep end in a race.

For a team like Marussia, with limited budget, it seems as though it is more cost effective to miss the odd race in exceptional circumstances rather than fund a reserve driver for a full season. For a team higher up the grid, such as Ferrari or McLaren, we would be more likely to see a reserve driver jump in to the car, particularly this year when the championships are still so close. We've seen Mark Webber race through broken bones in an attempt not to let his team down (and not to be replaced), how far will drivers have to go before a reserve driver is allowed to step in? We've also previously witnessed Ferrari struggle to find a replacement for Felipe Massa in 2009. They had a reserve driver lined up, but it took them three attempts to get a driver they were happy with.

Long summer

It's been a while since we've seen the need for a reserve driver. The last ill driver I can think of was Sergio Pérez, when he opted not to race after his accident in Monaco last year. Sauber didn't have a reserve driver ready either, and had to borrow super-sub Pedro de la Rosa for the weekend with just ten minutes warning.

The job will require them to be race-fit for an ever-growing number of weekends

The seasons are getting longer and longer, and whilst we have often raised concerns about the effect of so many races on the hard-working mechanics and crew, there's also the drivers to think of. Although very healthy athletes, the job will require them to be race-fit for an ever-growing number of weekends each year, with illness simply not allowed.

Some teams do appear to be doing the right thing. Force India, Williams, HRT and Caterham have given their Friday drivers plenty of opportunity, and you can imagine that they would be ready to jump into the car if required. This Marussia situation may be slightly different, in that they were waiting to see if Timo would be okay, hoping that he would be, and leaving it too late to do anything if he wasn't. Then again, this could be the kind of situation we see occur again, and it seems counter-intuitive to leave an empty grid slot. Marussia now have to rely on Charles Pic to continue their battle against HRT in the championship. He's still a rookie with a lot to learn, and the pressure is now on.

Whatever happens this weekend, or in the future of reserve driver racing, all we can say is get well Timo and come back soon!