League leaders Swansea City continued their best league start to a season in 103 years as Ronald's late strike earned all three points against Millwall in a game marred by allegations of racism.

The hosts had a number of big chances to take the lead in the first half at The Den, with Kyrell Lisbie, Mark Sykes and Jenson Metcalfe all coming close.

Swansea improved after the break, and were unable to turn the ball into the Millwall net during two different goalmouth scrambles which included the ball bouncing back off the post.

The match was brought to a halt midway through the second half as the officials spent close to eight minutes talking to both sets of coaches.

The stoppage was followed by a message over the speakers at the stadium stating there had been allegations of racist abuse aimed at Swansea's Ji-sung Eom.

With the game looking destined to finish goalless, Joseph Okopu's cross to the back post was met by substitute Ronald, who finished first-time to spark jubilant scenes in both the away end and on the Swansea bench.

Victory for Vitor Matos' side keeps their two-point cushion at the top of the Championship intact, while there is now a six-point gap to third.

Defeat for Alex Neil's Millwall sees them drop down to 10th.

The hosts had a glorious chance to take the lead after five minutes, as Mark Sykes got in behind Josh Tymon and looked to have found Lisbie for a tap-in, only for Filip Lissah to get a last-ditch toe to the ball and turn it behind for a corner.

And while the pressure continued to mount on the league leaders, they were thwarted at every turn.

With half-time approaching the Swans almost took the lead in comical style, as Millwall goalkeeper Filip Marschall came racing out of his box despite having two covering defenders, and his clearing kick bounced of Caleb Taylor and behind for a corner kick.

The visitors looked a different side after the break and came within a matter of inches away from taking the lead as a goalmouth scramble saw an initial effort bounce off the post and along the line before Jordi Osei-Tutu beat Joseph Opoku to the rebound to clear.

The game was stopped for seven minutes midway through the second half, as referee Edward Duckworth spoke to both benches in depth following allegations of racist chanting from the crowd.

From the restart Millwall sent a high cross into the Swansea box, and the nod down almost fell kindly to Sykes a few yards from goal, but Swans striker Ross Stewart was back defending to clear the danger.

Stewart was quickly involved at the other end, as he saw a low effort cleared off the line before yet another goalmouth scramble which Millwall eventually cleared.

In the 89th minute Millwall striker Lyndon Dykes was denied by Lawrence Vigouroux at close range after Tristan Crama had done well to keep a deep cross alive at the back post.

Fom the resulting corner Crama rose highest, but could not get his header on target, instead skimming the roof of the net.

Millwall were made to pay for their missed efforts throughout the game, as Swansea substitute Ronald met Opoku's cross at the back post and powered a first-time volley into the bottom corner.

Stewart almost added a second in the added eight minutes, but his effort flashed past the near post.

But it mattered not for the visitors, who are enjoying their best start to a league season since 1923.

Flashback to transfer deadline day and there were strong reports linking Swansea winger Ronald with a move to Millwall.

The Lions were believed to have agreed a fee of about £2m for the Brazilian, before the move collapsed at the final hour.

At the time Matos suggested that Ronald had been unable to agree terms with the London club.

Having been named among the substitutes at The Den, Ronald would have been eager to make an impact if called upon.

The 25-year-old has struggled at times to find a clinical edge for the Swans, scoring just 13 times in 121 games for the Welsh side.

And he was given just six minutes, plus added time, to make his impact.

But what an impact it was, finishing first time on the volley with the composure of a player thriving with confidence.

With all the injuries which have plagued Millwall's season to date, losing to a strike from a player who was so close to being on their books just over a month ago will sting just that little bit more.

Swansea City head coach Vitor Matos told BBC Sport Wales:

"It is a really hard place to come and a really tough team to play against, they make the game really hard to control.

"We knew that we needed to stay organised, keep concentration levels high, so I'm really proud of the boys for staying in the game and then we grew into it.

"It was a really mature performance, we had two more chances where we could have put the ball in the goal and then it was about believing we could score.

"And that's exactly what happened."