A rare defeat left his No. 1 ranking in jeopardy. Westwood followed up convincing group-stage wins at the World Match Play Championship by shooting a 67 in his final 16 match against Ryder Cup teammate Poulter. He still lost by 1 hole and could be supplanted as No. 1 by England's Luke Donald or German Martin Kaymer on Sunday.
Maybe he just isn't used to losing. But Westwood didn't mince his words.
"You know he's not going to hit it great but he's going to make a lot of putts and get up and down from everywhere, which was typical Ian today," Westwood said. "He had a few breaks as well.
"That's the frustrating thing about match play ... sometimes it's not reflective of how the players are playing."
Poulter was thrilled for the win against someone with whom he engages in regular Twitter banter. He did his best not to bite.
"I'm not going to get in a tennis match with Lee," said Poulter, before giving a solid defense of his game. "I played lovely. I hit three bad shots in that whole round of golf.
"I played pretty well this morning. Actually, I played very well. I shot a 66 to win that match. That's golf. I mean that's perfect match-play golf right there ... I played damn good."
Poulter was understandably delighted with his performance -- winless in 2011 and with only two top-10 finishes on tour, he hasn't had much to celebrate this year.
"I haven't done much for four months, so I'm not going to sit here and start welling up because I holed a few putts ... Give me a break," he said.
Westwood acknowledged his putter let him down to a certain extent against Poulter but couldn't hide his exasperation at the amount of breaks his opponent seemed to get, in his opinion.
Of the many "turning points" Westwood spoke of, the biggest came on the par-3 17 when the pair were all square. Poulter pulled his tee shot but the ball ran round the bank at the back-left of the green and rolled down, landing two feet away from the hole. Poulter tapped in for birdie and held his nerve on the last.
"He didn't hit a great shot at 17, wasn't aiming for the left fringe and comes down to two foot," Westwood said. "You have those days in match play."
Poulter, one of the circuit's great scramblers, acknowledged he had been fortunate on that occasion but again held back.
"Lee will be very frustrated about being 19 under through 45 holes [this week]. I'd be frustrated as well. I guess, I'm annoying to play against in the match-play format. I hole putts at the right time."
Poulter wasn't finished there on Saturday. In the afternoon, he won the last four holes -- making birdie on the final three -- in a terrific rally to beat Italy's Francesco Molinari by 2 holes in a tight quarterfinal.
He plays Belgium's Nicolas Colsaerts next with a place in the final at stake. With his matchplay pedigree, Poulter will be hard to beat.
"I wouldn't mind playing about six [match-play events] a year -- that would shorten my schedule nicely," Poulter said.
Westwood heads to Wentworth, England for next week's PGA Championship. He may tee off Thursday no longer at No. 1, despite recent tournament victories in Korea and Indonesia.
"My game is in great shape," he said.