Motherwell boss Stuart McCall was shocked his side failed to defeat St Mirren but had nothing but praise for the effort of his players.
McCall's men found themselves 2-0 down after two well-taken goals form Steven Thompson in the first half.
They fought back in the second half with Bob McHugh pulling one back in the 77th minute but despite bombarding their opponent's goal they could not find the equaliser.
McCall said: "I thought it was great entertainment and a terrific game. They took their chances, two terrific goals from Steven Thompson, a near-post finish and a back-post clinical header.
"I was disappointed to go in at half-time 2-0 down. It was an open game, we had opportunities and hit the woodwork, and failed to hit the target on other opportunities.
"The last 30 minutes was just a siege, they brought big (Lee) Mair on, brought (David) van Zanten on. I don't think they could have brought any more defenders on.
"How we never got an equaliser I'll never know. But I said to the boys, there are ways to lose games and I certainly want to go down fighting.
"We went right to the last minute, played some really good football and it just wasn't our night."
The capital club went three points clear at the top of the standings, for 24 hours at least, courtesy of strikes from Zlatan Ibrahimovic and Kevin Gameiro as well as an own goal from former PSG defender Bernard Mendy.
That came after Abdoulwhaid Sissoko was shown a straight red card for an ugly challenge on Argentinian forward Ezequiel Lavezzi in the 33rd minute.
It was Carlo Ancelotti's side's fifth triumph in a row in all competitions in a game they largely dominated.
The capital club came racing out of the traps, with Ibrahimovic firing narrowly wide from just outside the area.
Brest goalkeeper Alexis Thebaux then had to prevent the Sweden striker's backheel from Christophe Jallet's cross from finding the net.
And the 27-year-old shot-stopper had to be alert once more to keep out Thiago Silva's close-range header as well as Ibrahimovic's rebound.
At the other end, Mendy's volley forced a fine save from PSG goalkeeper Salvatore Sirigu, but their cause was not helped when they were reduced to 10 men after Sissoko saw red for a rash lunge at Lavezzi.
Javier Pastore saw his long-range effort kept out by Thebaux, who was at full stretch to deny Jallet's edge-of-the-area effort after the interval.
His goal was finally breached in the 54th minute, however, as Jallet's cross from the right was poked home by Ibrahimovic at the near post.
The former Barcelona and AC Milan striker could, and perhaps should, have doubled his side's lead after bursting through on goal, but his right-footed lob was kept out by Thebaux.
Ibrahimovic continued to cause havoc in the Brest defence and his audacious flick from the edge of the penalty area from Jeremy Menez's delivery missed the top corner by a whisker.
It seemed only a matter of time before PSG doubled their advantage and it came when Gameiro tapped in a rebound in the 72nd minute after Thebaux could only push Motta's cross to the France international.
To their credit, the hosts refused to lie down and Ahmed Kantari's header had to be cleared off the line by PSG defender Thiago Silva.
But Brest's misery was compounded in the first minute of added-on time when Mendy, who spent eight years at the Parc des Princes from 2000, could only direct his defensive header from Jallet's cross into his own net.
