diff --git a/src/mongo/s/balancer_policy.cpp b/src/mongo/s/balancer_policy.cpp
index 5d6e186..b8231d1 100644
--- a/src/mongo/s/balancer_policy.cpp
+++ b/src/mongo/s/balancer_policy.cpp
@@ -138,16 +138,35 @@ namespace mongo {
         // It is possible for a donor ('from') shard to have less chunks than a receiver one ('to')
         // if the donor is in draining mode.
 
-        if ( to.size() == 0 )
-            return from[0];
-
-        if ( from[0]["min"].Obj().woCompare( to[to.size()-1]["max"].Obj() , BSONObj() , false ) == 0 )
-            return from[0];
+        vector<BSONObj>::const_iterator ifrom = from.begin();
+        vector<BSONObj>::const_iterator ito = to.begin();
+        BSONObj chunk;
+        unsigned maxgap = 0;
+        do
+        {
+            // Seek to the following chunk on the receiver shard
+            while ( ito != to.end() && (*ifrom)["min"].Obj().woCompare( (*ito)["max"].Obj() , BSONObj() , false ) >= 0 )
+                ito++;
+
+            // Seek through the chunks on the donor shard until we catch up with the receiver,
+            // and count the span of the gap
+            unsigned gap = 0;
+            while ( ifrom != from.end() && ( ito == to.end() || (*ifrom)["max"].Obj().woCompare( (*ito)["min"].Obj() , BSONObj() , false ) <= 0 ) )
+            {
+                ifrom++;
+                gap++;
+            }
 
-        if ( from[from.size()-1]["max"].Obj().woCompare( to[0]["min"].Obj() , BSONObj() , false ) == 0 )
-            return from[from.size()-1];
+            // Pick the chunk in the middle of the widest gap
+            if ( gap > maxgap )
+            {
+                maxgap = gap;
+                chunk = *(ifrom - (gap/2 + 1));
+            }
+        }
+        while ( ifrom != from.end() && ito != to.end() );
 
-        return from[0];
+        return chunk;
     }
 
     bool BalancerPolicy::isSizeMaxed( BSONObj limits ) {