Former British swimming champion Karen Pickering has said that Rebecca Adlington faces an uphill struggle to reclaim the gold medal in the women's 400m freestyle.

Adlington secured victory in the event in Beijing 2008, but was fortunate to book a place in the last eight of this year's event with a time of 4:05.75 in the heats.

"It's always tough being in the first of the fast heats because you have to set the standard," BBC Sport quotes Pickering as saying.

"The 400m freestyle has changed a lot. You have girls like Schmitt who is a good 100m swimmer who can take the race out and then is strong enough to hang on.

"Becky doesn't have that speed. She is an 800m freestyle swimmer who comes down to the 400m - she's about endurance. It will be really tough for her to get a medal."

Adlington will compete in the women's 400m freestyle final from 8.18pm this evening.