• American walks out of after media questions about Florida crash • Five-times champion beats Elise Mertens 7-6, 6-4 in first round

A tearful Venus Williams walked out of her press conference on Monday after her first-round victory at Wimbledon, the American’s first match since her involvement in a fatal car accident in Florida that police allege she caused.

The No10 seed deflected a series of queries about the wrongful-death lawsuit filed on Thursday before she became overcome with emotion, prompting the moderator to request that journalists refrained from asking about the incident.

Venus Williams ‘at fault’ in fatal car crash, say Florida police Read more

“There are really no words to describe, like, how devastating and – yeah. I’m completely speechless. It’s just – yeah, I mean, I’m just …” a visibly shaken Williams said, her voice trailing off.

The seven-times major champion then broke down in tears, stepping out into the hallway to gather herself with members of her team.

Williams returned after about five minutes to field five more questions, mostly related to her 7-6 (7), 6-4 win against Belgium’s Elise Mertens amid wildly fluctuating weather on No1 Court, as the sun‑splashed afternoon gave way to blustery conditions and ultimately rain.

The American – at 37 the oldest woman in the draw here – was at her imperious best in the opening stages, breaking Mertens in her opening service game and dictating points with her serve. But Mertens, who was not born when Williams turned professional and only four when she won the first of her five Wimbledon singles titles, overcame those initial nerves and began challenging Williams with powerful groundstrokes into the corners and well-concealed variety.

Mertens blinked during the first-set tiebreak, then surrendered her early service break in the second. Rain interrupted play with the 21-year-old, who had just saved her second match point with a gorgeous backhand lob, serving at 3-5, 40-40 in the second set.

After a 33-minute delay Williams finished the job, uncorking an overhead smash to see off Mertens after an hour and 40 minutes and booking a second-round match against China’s Qiang Wang.

The American flashed her familiar smile after meeting her opponent at the net but it became clear during the press conference that her 20th appearance at the tournament she has won five times will be loaded with emotion.

“You can’t prepare for everything,” Williams said. “I have no idea what tomorrow will bring. That’s all I can say about it. That’s what I’ve learned.”

Palm Beach Gardens police said witnesses told investigators that Williams ran a red light in her Toyota Sequoia SUV at around 1pm on 9 June, injuring 79-year-old Jerome Barson, who died 13 days later. Barson was riding in the passenger seat when the Hyundai Accent driven by his wife, Linda, crashed into the side of Williams’s vehicle.

Williams told investigators she entered the six-lane intersection on a green light but was forced to stop midway through because of traffic ahead of her, failing to see the Barsons’ car when she continued through at about 5mph.

But police concluded the driver of Williams’s car “is at fault for violating the right of way”. Linda Barson, 68, also sustained injuries, including “a cracked sternum, shattered right arm, broken wrist, hand and fingers”.

Williams made her first public comments on the incident in a Facebook post on Friday night, describing herself as “heartbroken”.

One of only two former Wimbledon champions in the women’s field, Williams has a promising draw and perhaps a renewed ambition after her inspired run to the Australian Open final in January – a remarkable feat given the incurable autoimmune disease that has hamstrung her game for most of the decade.