BIRMINGHAM (Reuters) - Five-time champion Lin Dan said he had been learning from younger rivals as the Chinese kept alive his bid for a sixth All-England Championship title on Thursday.

The 31-year-old, who has played irregularly since 2012, showed the mental strength which produced two Olympic titles to secure a 21-15, 21-19 last-16 win over compatriot Tian Houwei.

Hard-hitting Tian threw everything at fifth-seeded Lin but could not build on mini-comebacks in each game.

"To have the correct attitude is crucial when you come up against these talented players," said Lin, referring to his 23-year-old opponent.

"Being a professional athlete, we all want to win the title. I can also learn from them and I'm more than happy to face the challenges they pose."

Lin's last-eight opponent is Kento Momota, the Japanese in surprising form this week, who edged past Marc Zwiebler of Germany, a former All-England semi-finalist.

Lin could face a potential semi-final meeting with world champion and holder Chen Long, who had little difficulty fending off Taiwan's Jen Hao-hsu 21-7, 21-9.

Earlier, Olympic bronze medallist Saina Nehwal saw the women's singles draw open up to her advantage but the Indian will first have to overturn a Chinese hoodoo.

Third seed Nehwal had to show speed, control and variation to see off Taiwan's Kim Hyo-min 21-15, 21-15, setting up a last-eight showdown with Wang Yihan, the 2009 All-England champion.

Nehwal has beaten Wang only once in nine meetings.

The winner will have an easier path to Sunday's final after Olympic champion Li Xuerui's surprise loss to compatriot Sun Yu.