Just Stop Oil protesters interrupted play twice at Wimbledon by throwing orange-coloured confetti and jigsaw pieces on to court 18.
The contest between Grigor Dimitrov and Sho Shimabukuro was interrupted by two protesters, who the All England Club said had been arrested.
A third protester then targeted Katie Boulter's match against Daria Saville.
Environmental protest group Just Stop Oil has targeted various sporting events, including an Ashes Test.
Followers of the group - which calls for the government to halt all new oil, gas and coal projects - also disrupted the rugby union Premiership final and the World Snooker Championship.
In a statement after the first episode, the All England Club (AELTC) said: "Following an incident on court 18, two individuals have been arrested on suspicion of aggravated trespass and criminal damage and these individuals have now been removed from the grounds."
A man and woman ran on to the court, throwing the confetti and jigsaw pieces from a Wimbledon 'Centre Court View' jigsaw puzzle box on to the grass.
A couple of hours later a man ran on to the same court, where British number one Boulter had just resumed her rain-interrupted first-round match against Australian Saville.
Just Stop Oil said in a statement its supporters had thrown "environmentally friendly orange confetti glitter and jigsaw pieces" and that "play was briefly delayed whilst marshals picked up the pieces".
Wimbledon the latest protest target despite increased security
Wimbledon organisers previously urged spectators to "be considerate" when they were asked about the possibility of climate change protests, and they also increased security checks at this year's event.
The tighter security had led on Monday to delays in getting fans into the grounds.
Despite the measures, Wimbledon became the latest sporting event to find its green surface turned briefly orange.
AELTC chief executive Sally Bolton said earlier this week the club had "taken account of what we've seen elsewhere so security has been uplifted in various places around the grounds".
An environmental activist previously tied themselves to the net post during the French Open semi-final between Casper Ruud and Marin Cilic in 2022.
'Scattered all across the court' - BBC eyewitness describes what she saw in first protest
Katie Smith on BBC Radio 5 Live
From my left-hand side two members of the public jumped on to the court, they both revealed Just Stop Oil T-shirts and they threw a box which revealed a lot of orange-golden confetti and some other blue material.
This box looked to be a jigsaw puzzle box ironically of Centre Court here at Wimbledon and that blue material that I have been describing has been revealed to be puzzle pieces and so this material scattered all across the court.
They then brought out ball boys and ball girls to remove it by hand, there were leaf blowers as well - and then the rain came down.
The police have just escorted the protesters around the outside the court, with a lot of reporters running to get pictures.