Notre Dame entered halftime trailing St. John's 37-34.
The absence of forward Luke Harangody, who is out with a bone bruise on his right knee, hasn't crippled the Irish, but it is being felt.
Notre Dame missed the 6-foot-8 senior the most during an 8-0 Red Storm run just past the midway point of the first half.
During opponents' runs like that one, which gave St. John's a 26-22 lead with 6:32 remaining in the first half, Notre Dame can usually stop them by finding Harangody down low on offense.
But the Irish were unable to use forward Tyrone Nash as that low-post run stopper during that time.
Nash did start to find some rhythm in the post in the final five minutes of the half.
The 6-foot-8 junior made a layup after getting the ball on the left block from Carleton Scott with 4:54 left in the half to cut the Irish's deficit to 30-28. With 2:05 left in the half, Nash scored from the left block again, cutting the Red Storm's lead to 35-33.
Nash will need to be even more of a factor in the post on offense in the second half.
He has held up OK on defense. St. John's had two offensive rebounds and scored only three second-chance points.
Nash, who is 14 pounds lighter than Harangody and not as broad shoulder, is easier to move down low, but he moves faster keeping passes down low at a minimum.
Scott has stepped up his game as far as rebounds. The 6-foot-7 junior had three in the first half. He averages 3.4 rebounds per game.
Notre Dame is still scoring in the paint, with 12 of its points coming inside the key in the first half. A lot of that is from the penetration of guard Ben Hansbrough.
Hansbrough scored 10 of the Irish's first 15 points mixing two three-pointers with two layups. Tim Abromaitis is leading Notre Dame's offense with 15 points.
Harangody would help in this game, but with St. John's hitting seven three-pointers in the first half, his absence isn't the reason the Irish trail at halftime.