Like the sweeper in a football team, Hong Kong's former No.2 official Carrie Lam is the one who clears up the mess during a crisis.

Barely a month into her job as Development Bureau chief in 2007, she was asked to talk to demonstrators who had gone on a hunger strike in protest against the demolition of Queen's Pier in Central.

Like a tough defender not afraid to lunge in for the tackle, she walked right into the angry crowd and told them to disperse so that demolition work could begin.

Even though the protesters kept shouting at her, she stood her ground and firmly repeated to them that keeping the pier was not an option.

The demolition went ahead eventually, and the episode earned her a reputation as a "good fighter".

The fighter in her surfaced when she was young. Mrs Lam grew up in a small flat, where she had to do her homework sitting on her bed. Even so, she always topped her class.

As a student at the University of Hong Kong, she started taking part in protests, including one against the government's handling of the Yau Ma Tei boat people.

She later switched her course of study from social work to sociology to help herself understand society.

But the former student activist ended up joining the government in 1980 at age 23 as an administrative officer because she wanted to bring about change.

At 26, she married mathematician Lam Siu Por, with whom she has two sons, aged 23 and 25.

Known to be a high flier and someone with strong principles, Mrs Lam rose up the ranks of the civil service. In 2007, she was appointed secretary for development by then Chief Executive Donald Tsang.

She performed well during her five years in this role, pressing ahead with initiatives to pursue sustainable development.

In 2012, she was promoted to the city's No.2 job, chief secretary.

As Mr Leung Chun Ying's deputy, she soon shone as a troubleshooter.

Her reputation as a capable and reasonable official was such that, in 2014, student leaders of the 79-day Umbrella Revolution, which saw protesters fill the streets to demand political reforms, asked to talk to her and not Mr Leung.

Mrs Lam did not cede any ground to the students, but the incident affected her popularity - some see her as basically similar to the hardline Mr Leung, but with a better image.

Analysts see her as Beijing's preferred choice for chief executive, noting how the central government approved her resignation as Chief Secretary in just days, while rival John Tsang's resignation took a month to be approved.

Still, even though she might have Beijing's support, she is trailing Mr Tsang in public popularity polls.

Unlike her rival, who reaches out to the public with a Facebook account and a blog, she does not have a presence on social media.

She could also be hit by a recent controversy over the Hong Kong Palace Museum in the Kowloon West Cultural District. She has been criticised for not consulting the public before signing a memorandum of understanding with Beijing to build the museum.

But Mrs Lam seems unfazed by the flak. At a press conference last Monday, she said: "I have never come across a single policy that was not controversial at all. If we are to avoid controversies and criticisms, the only way is not to do things."

Fighting words for the career civil servant who could become the city's first female chief executive.