* Milan take lead with early Robinho goal
* Barca retain two-point lead in Group H (Adds detail, fresh quotes)
By Terry Daley
ROME October 22 (Reuters) - Lionel Messi slipped past tight AC Milan marking to score in his first start since injury and give Barcelona a 1-1 draw on Tuesday that keeps them two points clear at the top of Champions League Group H.
The Argentine struck in the 23rd minute with a slick finish to a breakaway move to cancel out Robinho's stylish ninth minute opener, which came during a frantic opening period of pressure from the home side.
Barcelona moved up to seven points, with unbeaten Milan in second spot on five, two ahead of Celtic who beat Ajax 2-1 in Glasgow.
However, coach Gerardo Martino was less than happy with a point from a match he felt Barca should have won.
"I think with the way the match went we dropped two points tonight. A point isn't any good for us and we deserved more. We created chances and deserved to win," Argentine Martino told Sky Sport Italia.
"It didn't work for the first ten minutes of the match, we gave Milan the initiative. We didn't play like we did for the remaining 80 minutes and we paid for it."
Milan, who were missing three of their usual attackers from their starting line-up, including Mario Balotelli, came racing out of the blocks, putting pressure on Barca's backline and a defensive error led to Robinho's goal.
The Brazilian beat the away side's dithering defenders to a high bouncing ball, and after exchanging passes with revitalised-looking countryman Kaka, slid a simple finish past Victor Valdes.
"Kaka played extraordinarily well. He had to play almost as a full back in the second half," said Milan coach Massimiliano Allegri.
"To be a champions you can't only do it with your feet, but also with your head. Kaka showed that tonight once again."
The home side rarely looked troubled in the opening period, but found themselves back to square one only 14 minutes after scoring when they gave the ball away sloppily to Andres Iniesta.
The Spain midfielder picked up the otherwise excellent Cristian Zapata's misplaced pass and slipped in Messi on the right.
The Argentine cut inside and drilled low to level the score with his 63rd goal in 81 Champions League appearances just as he looked to have lost his footing.
Barca dominated the second half against a tired Milan, but despite a couple of good chances couldn't make the most of their possession and had to settle for a point.
"Milan were as we expected them to be, very tight. We couldn't find space but we tried to win the game and in the end a point isn't that bad for either side," Iniesta said.
Iniesta should have given his side the lead in the 55th minute when he collected Xavi's delicate pass and managed to break through Milan's stout backline, only to scuff his shot at full stretch and allow Marco Amelia to make a good save.
However, the best chance of the night fell to Robinho only two minutes beforehand, the Brazilian inexplicably letting the ball run past him after being brilliantly found by Sulley Muntari with only Valdes to beat and letting a famous win slip away. (Editing by Rex Gowar)