Benjamin's progress has been hampered by a groin injury

The Welshman clocked 45.67 seconds to go through in fourth place, but Robert Tobin and Graham Hedman went out.

Becky Lyne reached Thursday's 800m final, finishing in second place behind Russian Svetlana Klyuka.

Natasha Danvers-Smith finished third in her semi-final to qualify for Wednesday's 400m hurdles final, but Scot Lee McConnell just missed out.

Benjamin, who has been hampered by a persistent groin injury, was not happy with his performance.

"I tried to set myself up for a 44 seconds run. It's not good," said Benjamin.

"Mentally I was in a good place, but with 120m to go I didn't feel good. Medals are still up for grabs - I just have to adjust my tactics slightly.

I did what I came to do. I'm in the final where anything can happen Natasha Danvers-Smith

"I'm in the final but I'll have a bad lane. I didn't have the finish today and I faded."

Lyne was fourth coming round the final bend but finished strongly to clock one minute 59.11 seconds.

"I was a bit boxed in but knew not to panic and I'm surprised how fast it was," Lyne told BBC Sport. "I felt really good from 300m."

Russia's Olga Kotlyarova won a hard-fought first semi-final ahead of compatriot Svetlana Kotlyarova in two minutes 00.03 seconds.

Lyne's fellow Brit Jemma Simpson finished back in sixth place and with only three automatic qualifying places up for grabs did not reach the final.

Amanda Pritchard won her appeal after she was brought down in the heats but withdrew injured and did not take her place in the semi-finals.

Commonwealth silver medallist Danvers-Smith had a mixed race over the hurdles and clocked 55.14 as she eased up over the line.

Maduaka clocked 11.24 in her 100m heat

"The main objective was to qualify and run a controlled race," she said. "I did want I came to do and I'm in the final where anything can happen."

Yevgeniya Isakova won the semi in a personal best time of 54.17.

McConnell stuttered over the final hurdle in the first semi and finished fifth in 55.61 seconds.

"I was OK until the last hurdle but I hit it and lost too much momentum," said McConnell.

Greek Olympic champion Fani Halkia won the first semi-final in 54.57 while German Claudia Marx set a new personal best to finish second in 54.80.

Marilyn Okoro and Nicola Sanders impressed in the 400m opening heats as Russia's Olga Zaytseva and Bulgaria's Vanya Stambolova looked in imperious form.

Okoro ran a personal best of 52.02 seconds, while Ireland's Joanne Cuddihy also qualified in 51.41.

Joice Maduaka, Anyika Onuora and Emma Ania all progressed to Wednesday's 100m semi-finals.

A change of coaches to American Thomas Johnson seems to have paid off for Maduaka as she cruised to the next round with a time of 11.24 seconds.

Belgium's Kim Gevaert was the quickest qualifier in 11.19 while veteran Merlene Ottey also went through, finishing third in Maduaka's heat in 11.41.